The York/MIREC Studies - FAQ References

Comments on current issues in fluoride/thyroid research.
Post Reply
Posts: 126
Joined: Mon Apr 03, 2006 5:51 am

The York/MIREC Studies - FAQ References

Post by wendy »

The papers below are referenced in the ongoing FAQ forum about the MIREC/fluoride studies conducted by Till et al. at York University.

Unfortunately, it has become necessary to address these studies in greater detail, as so much incorrect and misleading information is presented.

We mean no malice to the authors. Our issue is with their methods and their words.

This page will be updated as time allows and will contain all studies referenced in the FAQ. - WS

SYNOPSIS: MIREC data shows that IQ loss, as reported in the York studies, is likely due to iodine-induced thyroid dysfunction, not fluoride. Mean iodine intake was 444 μg/day for the cohort (Hall et al., 2023). (The WHO recommends 250 μg/day during pregnancy and lactation.) 88% percent of the pregnant women took prenatal vitamin supplements, which in Canada usually contain 220 μg of potassium iodide. At rapid chronic iodine intake levels this high, and fluoride levels as low as documented, iodine toxicity will be predominant. (This iodine intake may also affect urinary fluoride levels, further obfuscating results.) Authors used false "adequate" ranges for iodine sufficiency during pregnancy, and never did account for the high iodine intake.


Aakre I, Strand TA, Moubarek K, Barikmo I, Henjum S - "Associations between thyroid dysfunction and developmental status in children with excessive iodine status" PLoS One 12(11):e0187241 (2017) doi: 10.1371/journal.pone.0187241 ... ne.0187241
"We found an association between thyroid dysfunction and poorer developmental status among children with excessive iodine intake...With iodine excess being an increasing problem globally, this subject should be further explored."
(NOTE: In Canada, more than half of the children 3-5 years old are consuming too much iodine. 40% are consuming "excessive" amounts. This was never considered by the York team who investigated children at that age.)

Aakre I, Bjøro T, Norheim I, Strand TA, Barikmo I, Henjum S - "Development of thyroid dysfunction among women with excessive iodine intake--A 3-year follow-up" J Trace Elem Med Biol 31:61-6 (2015) doi: 10.1016/j.jtemb.2015.03.004 ... 2X15000346

Abbassi-Ghanavati M, Greer LG, Cunningham FG - “Pregnancy and Laboratory Studies” Obstetrics & Gynecology 114(6):1326–1331 (2009) doi:10.1097/aog.0b013e3181c2bde8

Abel MH, Korevaar TIM, Erlund I, Villanger GD, Caspersen IH, Arohonka P, Alexander J, Meltzer HM, Brantsæter AL - "Iodine Intake is Associated with Thyroid Function in Mild to Moderately Iodine Deficient Pregnant Women" Thyroid 28(10):1359-1371 (2018) doi: 10.1089/thy.2018.0305. MoBa

Abel MH, Caspersen IH, Meltzer HM, Haugen M, Brandlistuen RE, Aase H, Alexander J, Torheim LE, Brantsæter AL - "Suboptimal Maternal Iodine Intake Is Associated with Impaired Child Neurodevelopment at 3 Years of Age in the Norwegian Mother and Child Cohort Study" J Nutr 147(7):1314-1324 (2014) MoBa

Abel MH, Ystrom E, Caspersen IH, Meltzer HM, Aase H, Torheim LE, Askeland RB, Reichborn-Kjennerud T, Brantsæter AL - "Maternal Iodine Intake and Offspring Attention-Deficit/Hyperactivity Disorder: Results from a Large Prospective Cohort Study" Nutrients 9(11):1239 (2017) doi: 10.3390/nu9111239 MoBa
"The maternal use of supplemental iodine was associated with an increased risk of child ADHD diagnosis and a higher mean ADHD symptom score...Initiating iodine supplement use in the first trimester was associated with an increased risk of ADHD diagnosis, whereas use before pregnancy was associated with increased child ADHD symptom scores."

Aboutorabi R, Rajaban R, Keykhaei N - "Relation of hyperthyroidism with urine volume and Specific Gravity" Medical Journal of Mashad University of Medical Sciences 47(83):57-61 (2004)
"We found significant increase in urine volume (p<0.001) and decrease in specific gravity in patients with hyperthyroidism (p<0.001)."

Ahmad S, Bailey EH, Arshad M, Ahmed S, Watts MJ, Stewart AG, Young SD - "Environmental and human iodine and selenium status: lessons from Gilgit-Baltistan, North-East Pakistan" Environ Geochem Health 43(11):4665-4686 (2021) doi: 10.1007/s10653-021-00943-w ... 21-00943-w
"The hydration correction with creatinine significantly influenced the rate of I deficiency or sufficiency in different age groups, which is concerning since UICuncor and UICsg remained consistent across age groups...we do not recommend the use of creatinine as a corrective factor in UIC surveys."

Alsayed A, Gad AM, Abdel-Baset H, Abdel-Fattah A, Ahmed A, Azab A - "Excess urinary iodine is associated with autoimmune subclinical hypothyroidism among Egyptian women" Endocr J 55(3):601-5 (2008) doi: 10.1507/endocrj.k07e-165 ... 5/_article

Althubaiti A - "Information bias in health research: definition, pitfalls, and adjustment methods" J Multidiscip Healthc 9:211-7 (2016) doi: 10.2147/JMDH.S104807

Andersen SL, Sørensen LK, Krejbjerg A, Møller M, Laurberg P - "Challenges in the evaluation of urinary iodine status in pregnancy: the importance of iodine supplement intake and time of sampling" Eur Thyroid J 3(3):179-88 (2014)
"Time of spot urine sampling and time span from iodine supplement intake to spot urine sampling should be considered when evaluating urinary iodine status in pregnancy."

Andersen SL, Laurberg P - “Iodine Supplementation in Pregnancy and the Dilemma of Ambiguous Recommendations” Eur Thyroid J 5(1):35-43 (2016) doi: 10.1159/000444254 ... 444254.xml

Andersen S, Waagepetersen R, Laurberg P - "Misclassification of iodine intake level from morning spot urine samples with high iodine excretion among Inuit and non-Inuit in Greenland" Br J Nutr 113(9):1433-40 (2015). doi: 10.1017/S0007114515000653 ... D3632C5B8B
"Iodine excretion was lower in morning spot urine samples than in 24 h urine samples (P< 0.001). This difference was associated with iodine intake levels (P< 0.001), and was statistically significant when the iodine excretion level was above 150 μg/24 h. In conclusion, the iodine intake level was underestimated from morning spot urine samples if iodine excretion was above the recommended level."

Andersen MS, Jensen TK, Dreyer AF, Madsen JB, Christesen HT, Brandslund I, Bilenberg N, Glintborg D - "Free thyroxine in early pregnancy is an independent negative predictor of 3rd trimester HbA1c. Odense child cohort" Clin Endocrinol (Oxf) 95(3):508-519 (2021). doi: 10.1111/cen.14492 ODENSE - OCC

Arbuckle TE, Fraser WD, Fisher M, et al. - “Cohort profile: the maternal-infant research on environmental chemicals research platform” Paediatr Perinat Epidemiol 27(4):415-25 (2013) doi: 10.1111/ppe.12061 MIREC

Arbuckle TE, Davis K, Marro L, Fisher M, Legrand M, LeBlanc A, Gaudreau E, Foster WG, Choeurng V, Fraser WD; MIREC Study Group - "Phthalate and bisphenol A exposure among pregnant women in Canada--results from the MIREC study" Environ Int 68:55-65 (2014) doi: 10.1016/j.envint.2014.02.010 MIREC ... 2014000609

Asvold BO, Bjøro T, Vatten LJ - "Association of thyroid function with estimated glomerular filtration rate in a population-based study: the HUNT study" Eur J Endocrinol 164(1):101-5 (2011) doi: 10.1530/EJE-10-0705 ... /1/101.xml
"These findings suggest that low thyroid function, also within the clinically normal range, is associated with reduced GFR."
See many other studies on thyroid function/TSH and GFR/creatinine excretion (PFPC Members): viewtopic.php?p=5105#p5105

Ba Y, Ren LJ, Yin G, et al. - "Effect of different fluoride and iodine concentrations in drinking water on children's dental fluorosis and thyroid function" Chinese Journal of Public Health 25(8):942-943 (2009)
"High iodine increases the concentration of FT4. Fluoride can increase the concentration of FT4 under high iodine conditions."

Bailote HB, Linhares D, Carvalho C, Prazeres S, Rodrigues AS, Garcia P - "Iodine Intake and Related Cognitive Function Impairments in Elementary Schoolchildren" Biology (Basel) 11(10):1507 (2022) doi: 10.3390/biology11101507

Baldi E, Bucherelli C - "The inverted 'u-shaped' dose-effect relationships in learning and memory: modulation of arousal and consolidation" Nonlinearity Biol Toxicol Med 3(1):9-21 (2005) doi: 10.2201/nonlin.003.01.002

Bashash M, Thomas D, Hu H, Martinez-Mier EA, Sanchez BN, Basu N, Peterson KE, Ettinger AS, Wright R, Zhang Z, Liu Y, Schnaas L, Mercado-García A, Téllez-Rojo MM, Hernández-Avila M - "Prenatal Fluoride Exposure and Cognitive Outcomes in Children at 4 and 6-12 Years of Age in Mexico" Environ Health Perspect 125(9):097017 (2017) doi: 10.1289/EHP655 ELEMENT
NOTE: No consideration given to thyroid status and iodine intake in mothers or children. [Iodine intake is deemed excessive in at least a third of Mexican children at ages specified, as well as a third of healthy adults in Mexico City, home of the ELEMENT cohort (Flores-Rebollar et al., 2014; Gonzalez-Nunez et al., 2021).]

Bath SC, Steer CD, Golding J - "Effect of inadequate iodine status in UK pregnant women on cognitive outcomes on their children: results from the Avon Longitudinal Study of Parents and Children (ALSPAC)" Lancet 382: 331–337 (2013) ALSPAC ... 5/fulltext

Beck IH, Bilenberg N, Möller S, Nielsen F, Grandjean P, Højsager FD, Halldorsson TI, Nielsen C, Jensen TK - "Association between prenatal and early postnatal exposure to perfluoroalkyl substances (PFAS) and IQ score in 7-year-old children from the Odense Child Cohort" Am J Epidemiol. 2023 Apr 29:kwad110. doi: 10.1093/aje/kwad110 ODENSE - OCC ... 10/7146879

Bernal J - "Thyroid Hormones in Brain Development and Function", In: Feingold KR, Anawalt B, Blackman MR, Boyce A, Chrousos G, Corpas E, de Herder WW, Dhatariya K, Dungan K, Hofland J, Kalra S, Kaltsas G, Kapoor N, Koch C, Kopp P, Korbonits M, Kovacs CS, Kuohung W, Laferrère B, Levy M, McGee EA, McLachlan R, New M, Purnell J, Sahay R, Shah AS, Singer F, Sperling MA, Stratakis CA, Trence DL, Wilson DP, editors. Endotext [Internet]. South Dartmouth (MA):, Inc.; 2000–. (May 2022)

Bertinato J, Gaudet J, De Silva N, Mohanty S, Qiao C, Herod M, Gharibeh N, Weiler H - "Iodine Status of Mother-Infant Dyads from Montréal, Canada: Secondary Analyses of a Vitamin D Supplementation Trial in Breastfed Infants" J Nutr 152(6):1459-1466 (2022) doi: 10.1093/jn/nxac047
"The percentages of mothers that used a multivitamin-mineral (MVM) supplement containing iodine were 90% in pregnancy and 79% and 59% at 1 and 6 months of lactation, respectively." - ->see formula study by Till et al. (2020)

Bertinato J, Qiao C, L'Abbé MR - “Iodine Status of Canadian Children, Adolescents, and Women of Childbearing Age” J Nutr 151(12):3710-3717 (2021) doi: 10.1093/jn/nxab268

Bliddal S, Boas M, Hilsted L, Friis-Hansen L, Juul A, Larsen T, Tabor A, Faber J, Precht DH, Feldt-Rasmussen U - "Increase in thyroglobulin antibody and thyroid peroxidase antibody levels, but not preterm birth-rate, in pregnant Danish women upon iodine fortification" Eur J Endocrinol 176(5):603-612 (2017) doi: 10.1530/EJE-16-0987
(Increase in thyroglobulin antibody and thyroid peroxidase antibody levels in pregnant Danish women upon iodine fortification)

Bu Y, Cai Y, Ji C, Zhao C, Tian C, Pang B, Shi M, Li X, Liu Y, Sun D - “Evaluation of iodine nutritional status during pregnancy by estimated 24-h urinary iodine excretion: population variation range and individual accuracy” Public Health Nutr 25(2):237-247 (2022). doi: 10.1017/S1368980021003335 ... C6BA9C9B7F
MIREC urine samples were non-fasting, and taken throughout the day (see Arbuckle, 2014 for details.) York/IQ studies never disclosed sampling times. Highly suspect, as is "correcting for creatinine".
Especially during the first trimester, UIC/Cr may vary drastically between morning and afternoon/evening samples.
  • Excerpt, Table 1 (Supplement, Bu et al., 2022)
Bülow Pedersen I, Knudsen N, Jørgensen T, Perrild H, Ovesen L, Laurberg P - "Large differences in incidences of overt hyper- and hypothyroidism associated with a small difference in iodine intake: a prospective comparative register-based population survey" J Clin Endocrinol Metab 87(10):4462-9 (2002) doi: 10.1210/jc.2002-020750 ... 62/2846385
"The results of this prospective investigation of the incidence of overt hyper- and hypothyroidism suggest that iodine supplementation of a population may increase the incidence of overt hypothyroidism, even if the population is moderately iodine-deficient. In such a population, the increase in risk of hypothyroidism should be weighed against the risk of ID disorders such as hyperthyroidism due to multinodular toxic goiter."

Candido AC, Vieira AA, de Souza Ferreira E, Moreira TR, do Carmo Castro Franceschini S, Cotta RMM - "Prevalence of Excessive Iodine Intake in Pregnancy and Its Health Consequences: Systematic Review and Meta-analysis" Biol Trace Elem Res 201(6):2784-2794 (2023) doi: 10.1007/s12011-022-03401-5 ... 22-03401-5
"The prevalence of excessive iodine intake in 10,736 pregnant women in different regions of the world was 52%."

Carvalho IP, Peixoto B, Caldas JC, Costa A, Silva S, Moreira B, Almeida A, Moreira-Rosário A, Guerra A, Delerue-Matos C, Sintra D, Pestana D, Pinto E, Mendes FC, Martins I, Leite JC, Fontoura M, Maia ML, Queirós P, Moreira R, Leal S, Norberto S, Costa V, Fernandes VC, Keating E, Azevedo L, Calhau C - "Association between Elevated Iodine Intake and IQ among School Children in Portugal" Nutrients 14(21):4493 (2022) doi: 10.3390/nu14214493 IoGeneration Project (one-spot, first-morning urine samples)
"A greater proportion of children in the ≥250 µg/g group had below-average IQs, compared to children with less than 250 µg/g (p = 0.037)...The proportion of below-average IQs increased with increasingly elevated iodine concentrations (p = 0.047). The association remained significant after the adjustment for confounders, with the elevated iodine group showing increased odds of having below-average IQs when compared with the non-elevated iodine group (OR 1.55; 95% CI 1.11–2.17; p = 0.011). Consistently, the former group presented a lower mean IQ than the latter (p = 0.006)." [--> see also: UIC levels in Xiang IQ studies]

Chen J, Zhu J, Huang X, Zhao S, Xiang H, Zhou P, Zhou T, Xu Z - "Subclinical Hypothyroidism with Negative for Thyroid Peroxidase Antibodies in Pregnancy: Intellectual Development of Offspring" Thyroid 32(4):449-458 (2022) doi: 10.1089/thy.2021.0374
"The effects of the intellectual development of the offspring with SCH-TPOAb- are related to the level of TSH."

Chen W, Sang Z, Tan L, Zhang S, Dong F, Chu Z, Wei W, Zhao N, Zhang G, Yao Z, Shen J, Zhang W - "Neonatal thyroid function born to mothers living with long-term excessive iodine intake from drinking water" Clin Endocrinol (Oxf) 83(3):399-404 (2015)
"Mothers living in HI areas (β = 0·296, 95% CI: 0·163, 0·255) and with subclinical hypothyroidism (β = 0·360, 95% CI: 0·034, 0·175) contributed to elevated cord blood TSH concentration in neonates, while male neonates were more likely to present with higher TSH concentration compared with female infants (β = -0·760, 95% CI: -0·119, -0·033). Conclusions: Excessive iodine intake during pregnancy was associated with an increased rate of hyperthyrotropinaemia in neonates and their mothers, especially in male neonates."

Chen W, Zhang Y, Hao Y, Wang W, Tan L, Bian J, Pearce EN, Zimmermann MB, Shen J, Zhang W - "Adverse effects on thyroid of Chinese children exposed to long-term iodine excess: optimal and safe Tolerable Upper Intake Levels of iodine for 7- to 14-y-old children" Am J Clin Nutr 107(5):780-788 (2018) doi: 10.1093/ajcn/nqy011
"We recommend 250 and 300 μg/d as safe Tolerable Upper Intake Levels of iodine for children aged 7-10 y and 11-14 y, respectively."

Chen X, Yu J, Huang Y, Chen G - "Comparison of cognitive function in patients with hypothyroidism and subclinical hypothyroidism" Chinese Behavioral Medical Sciences 17(12):1078-1079 (2008) ... d=28958907

Cheung KL, Lafayette RA - "Renal physiology of pregnancy" Adv Chronic Kidney Dis 20(3):209-14 (2013) doi: 10.1053/j.ackd.2013.01.012
"During pregnancy, the GFR increases 50% compared with prepregnancy levels."

Chung HR - “Iodine and thyroid function” Ann Pediatr Endocrinol Metab 19(1):8-12 (2014) doi: 10.6065/apem.2014.19.1.8

Chung JH - "Recent Issues Related to Thyroid Disease in Pregnancy" Int J Thyroidol 13(2):85-94 (2020)
(L-T4 therapy is not recommended in TPOAb-positive pregnant women to reduce miscarriage.)

Cools R, D'Esposito M - "Inverted-U-shaped dopamine actions on human working memory and cognitive control" Biol Psychiatry 69(12):e113-25 (2011) doi: 10.1016/j.biopsych.2011.03.028
https://www.biologicalpsychiatryjournal ... 2/fulltext
"The relationship between cognitive performance and dopamine (DA) levels follows an 'Inverted-U–shaped' function, where both too little and too much DA impairs performance." (See Goldman-Rakic et al., 2000)

Connelly KJ, Boston BA, Pearce EN, Sesser D, Snyder D, Braverman LE, Pino S, LaFranchi SH - "Congenital hypothyroidism caused by excess prenatal maternal iodine ingestion" J Pediatr 161(4):760–762 (2012)

Cong Xuzi, Li Fucheng, Jiang Zehai, Li Fei, Yang Ying, Yan Shulin - "Analysis of the relationship between salt iodization and iodine deficiency disorders, coal-burning fluorosis and urinary iodine and fluoride" Contemporary Medicine (2012)

Corcino CM, Berbara TMBL, Saraiva DA, Morais NAOES, Schtscherbyna A, Gertrudes LN, Teixeira PFDS, Vaisman M - "Variation of iodine status during pregnancy and its associations with thyroid function in women from Rio de Janeiro, Brazil" Public Health Nutr 22(7):1232-1240 (2019) ... 8A5A589253
"Maternal UIC was above the normal range (≥250 µ/l) in >40 % of the analysed samples and excessive (≥500 µ/l) in 6·4 % of the samples. Women with median UIC≥250 µg/l and at least one sample showing excessive UIC had a 6·6- fold increased risk of presenting SCH at some point during gestation."

Cortés-Castell E, Juste M, Palazón-Bru A, Goicoechea M, Gil-Guillén VF, Rizo-Baeza MM - "Factors associated with moderate neonatal hyperthyrotropinemia" PLoS One 14(7):e0220040 (2019) doi: 10.1371/journal.pone.0220040 ... ne.0220040

Cui Yushan, Zhao Liang, Zeng Qiang, Wang Rui, Zhang Lei, Fu Gang, Feng Baojia, Liu Hongliang - "The role of oxidative stress in iodine and fluoride induced thyroid injury" Environmental and Occupational Medicine (1):7-12 (2016)

Cui Y, Zhang B, Zhang Z, Nie J, Liu H - "Long-term repetitive exposure to excess iodine induces mitochondrial apoptosis, and alters monoamine neurotransmitters in hippocampus of rats of different genders" Toxicol Res (Camb) 10(5):975-982 (2021)
"The results showed that excess iodine could increase urinary iodine and brain organ coefficient in offspring of both genders, change the hippocampal cell structure, and damage the spatial learning and memory capacities. ... Besides, excess iodine showed different effects on monoamine neurotransmitter in different gender."

Cui T, Wang W, Chen W, Pan Z, Gao S, Tan L, Pearce EN, Zimmermann MB, Shen J, Zhang W - "Serum Iodine Is Correlated with Iodine Intake and Thyroid Function in School-Age Children from a Sufficient-to-Excessive Iodine Intake Area" J Nutr 149(6):1012-1018 (2019) doi: 10.1093/jn/nxy325 ... 6622166289
"The median iodine intake was estimated to be 299 μg/d and was significantly higher in boys than in girls (316 μg/d compared with 283 μg/d; P < 0.001)...Serum iodine was positively correlated with iodine intake and the serum FT4 concentration in children. It is a potential biomarker for diagnosing excessive iodine intake in children."

Cui Y, Yu J, Zhang B, Guo B, Gao T, Liu H - "The relationships between thyroid-stimulating hormone and/or dopamine levels in peripheral blood and IQ in children with different urinary iodine concentrations" Neurosci Lett 729:134981 (2020) doi: 10.1016/j.neulet.2020.134981 ... 4020302512
"The proportion of people with low average and lower intelligence in UIC ≥ 300 μg/L group was significantly higher than that in control group..."

Derakhshan A, Kortenkamp A, Shu H, Broeren MAC, Lindh CH, Peeters RP, Bornehag CG, Demeneix B, Korevaar TIM - "Association of per- and polyfluoroalkyl substances with thyroid homeostasis during pregnancy in the SELMA study" Environ Int 167:107420 (2022). doi: 10.1016/j.envint.2022.107420 SELMA ... 2022003476
"Higher PFUnDA levels were associated with lower TT4 (β [95% CI]: -1.58 [-3.07 to -0.09]) and there was an inverted U-shaped association of PFOS with TT4 (P = 0.03). Higher PFDA, PFUnDA, PFHpA levels were associated with a lower TT3. Overall, higher PFAS concentrations were associated with a higher FT4/FT3 ratio and a higher TT4/TT3 ratio. There was no association of PFAS with the TSH/FT4 ratio. Higher concentrations of several PFAS were associated with lower TT4/FT4 and TT3/FT3 ratios."

Dong J, Liu S, Wang L, Zhou X, Zhou Q, Liu C, Zhu J, Yuan W, Xu WY, Deng J - "Iodine monitoring models contribute to avoid adverse birth outcomes related more than adequate iodine intake" BMC Pregnancy Childbirth 21(1):454 (2021)
https://bmcpregnancychildbirth.biomedce ... 21-03936-w
"Multivariate logistic regression analysis showed that multivitamin supplements containing iodine and milk consumption were risk factors for more than adequate iodine (UIC ≥ 250 μg/L). Iodine-rich diet was significantly related to heavier birthweight, larger head circumference and longer femur length of the newborns while more than adequate iodine intake (UIC ≥ 250 μg/L) was a risk factor for macrosomia."

Du Y, An N, Hu Y, Duan L, Ma J, Huang H, ZhuJ, Sun L, Li Z, Ba Y - "IQ Alterations in Children at 7-13 Years Old: The Roles of Prenatal and Childhood Fluoride Exposure" Conference Proceedings, The 8th International Conference on Medical Geology (2019) ... .-2019.pdf
"Prenatal fluoride exposure in drinking water could cause loss of children's IQ, especially in the proportion of children with excellent and extremely excellent IQ grades....When urinary fluoride level does not exceed 0.9 mg/L, children's IQ increases with the increase of urinary fluoride level (P<0.05)....For every 0.1 mg L-1 increase in urinary fluoride, children's IQ score increased by 0.12 in multiple adjustment regression analysis...appropriate concentration of fluoride exposure in childhood may improve intellectual development of children in some degree." Iodine-excessive area - average UIC -> 396 ug/L
SEE also: Wang/Yang/Hong studies

Du Y, Gao Y, Meng F, Liu S, Fan Z, Wu J, Sun D - "Iodine deficiency and excess coexist in China and induce thyroid dysfunction and disease: a cross-sectional study" PLoS One 9(11):e111937 (2014) doi: 10.1371/journal.pone.0111937 ... ne.0111937
"Thyroid nodules are more likely to be present in the iodine excess and deficient areas than in the iodine sufficient areas. Subclinical hyperthyroidism and overt hyperthyroidism are more likely to be prevalent in the iodine-deficient areas than in the iodine excess or sufficient areas. Subclinical hypothyroidism is more likely to be prevalent in the high iodine intake areas than in the iodine deficient or sufficient areas. Median TSH may be deemed as an alternative indicator for monitoring the iodine nutrition status of the adult population in iodine excess and deficient areas."

Fan P, Chen Y, Luo ZC, Shen L, Wang W, Liu Z, Zhang J, Ouyang F - "Cord Blood Thyroid Hormones and Neurodevelopment in 2-Year-Old Boys and Girls" Front Nutr 8:773965 (2021) doi: 10.3389/fnut.2021.773965 ... 73965/full
"Mild alterations in thyroid hormones of newborns were associated adversely with neurodevelopment in boys, suggesting the importance of optimal thyroid hormone status for neurodevelopment in early life."

Farebrother J, Zimmermann MB, Andersson M - "Excess iodine intake: sources, assessment, and effects on thyroid function" Ann N Y Acad Sci. 1446(1):44-65 (2019) doi: 10.1111/nyas.14041 ... nyas.14041

Farmus L, Till C, Green R, Hornung R, Martinez Mier EA, Ayotte P, Muckle G, Lanphear BP, Flora DB - "Critical windows of fluoride neurotoxicity in Canadian children" Environ Res 200:111315 (2021) doi: 10.1016/j.envres.2021.111315 MIREC ... 5121006095

Fields EM - "Treatment of metabolic insufficiency and hypothyroidism with sodium liothyronine; preliminary report" J Am Med Assoc 163(10):817-21 (1957) doi: 10.1001/jama.1957.02970450019006
(re: early reports of specific gravity change with T3 treatment)

Flores-Rebollar A, Lendechy Velázquez M, Castro Sánchez A, López Carrasco G, Ruiz Juvera A - "Urinary iodine excretion in healthy Mexican adults" Arch Latinoam Nutr. 64(3):153-60 (2014) -> Mexico City
"Excessive dietary iodine intake was established in 31.4% of all volunteers according to their UI, placing them at risk of thyroid dysfunction."

Flores-Rebollar A, Moreno-Castañeda L, Vega-Servín NS, López-Carrasco G, Ruiz-Juvera A - "Prevalence of autoimmune thyroiditis and thyroid dysfunction in healthy adult Mexicans with a slightly excessive iodine intake" Nutr Hosp 32(2):918-24 (2015). doi: 10.3305/nh.2015.32.2.9246
"Median UI was 267 μg/L, (IQR 161.3 - 482.5) spite of our study's limitations, the frequency of autoimmune thyroiditis is clearly elevated in the studied population. Further studies are necessary in order to define the prevalence of autoimmune thyroid disease as well as the current iodine nutritional status in our country."

Freire C, Ramos R, Amaya E, Fernández MF, Santiago-Fernández P, Lopez-Espinosa MJ, Arrebola JP, Olea N - "Newborn TSH concentration and its association with cognitive development in healthy boys" Eur J Endocrinol 163(6):901-9 (2010) INMA-Granada
"Newborn thyroid hormone status expressed by TSH in cord blood may adversely affect later cognitive function."

Furnée CA, van der Haar F, West CE, Hautvast JG - "A critical appraisal of goiter assessment and the ratio of urinary iodine to creatinine for evaluating iodine status" Am J Clin Nutr 59(6):1415-7 (1994) doi: 10.1093/ajcn/59.6.1415 ... 15/4715926
"Further, the urinary iodine-creatinine ratio correlated significantly with the creatinine concentration; Spearman's rank-order correlation coefficient, rs= 0.39 (P < 0.001). If creatinine is a suitable index to correct for variations in iodine excretion, no correlation would be expected."

Gao TS, Teng WP, Shan ZY, Jin Y, Guan HX, Teng XC, Yang F, Wang WB, Shi XG, Tong YJ, Li D, Chen W - "Effect of different iodine intake on schoolchildren's thyroid diseases and intelligence in rural areas" Chin Med J (Engl) 117(10):1518-22 (2004)

Gao M, Chen W, Sun H, Fan L, Wang W, Du C, Chen Y, Lin L, Pearce EN, Shen J, Cheng Y, Wang C, Zhang W - "Excessive iodine intake is associated with formation of thyroid nodules in pregnant Chinese women" Nutr Res 66:61-67 (2019) doi: 10.1016/j.nutres.2019.02.009 ... 1718307814

Gerber B, Guggenberger R, Fasler D, Nair G, Manz MG, Stussi G, Schanz U - "Reversible skeletal disease and high fluoride serum levels in hematologic patients receiving voriconazole" Blood 120(12):2390-4 (2012) doi: 10.1182/blood-2012-01-403030 ... 712051687X

Ghassabian A, Bongers-Schokking JJ, de Rijke YB, van Mil N, Jaddoe VW, de Muinck Keizer-Schrama SM, Hooijkaas H, Hofman A, Visser W, Roman GC, Visser TJ, Verhulst FC, Tiemeier H - "Maternal thyroid autoimmunity during pregnancy and the risk of attention deficit/hyperactivity problems in children: the Generation R Study" Thyroid 22(2):178-86 (2012). doi: 10.1089/thy.2011.0318 Generation R
"In particular, children of TPOAb-positive mothers were at a higher risk of attention deficit/hyperactivity problems (OR=1.77, 95% CI: 1.15–2.72, p=0.01)."

Ghassabian A, Bongers-Schokking JJ, Henrichs J, Jaddoe VW, Visser TJ, Visser W, de Muinck Keizer-Schrama SM, Hooijkaas H, Steegers EA, Hofman A, Verhulst FC, van der Ende J, de Rijke YB, Tiemeier H - "Maternal thyroid function during pregnancy and behavioral problems in the offspring: the generation R study" Pediatr Res 69(5 Pt 1):454-9 (2011) doi: 10.1203/PDR.0b013e3182125b0c Generation R
"The linear relationship with more externalizing scores was across the range of TSH; this implies that subtle impairments of maternal thyroid function may affect the child. The results suggest that thyroid function is crucial for fetal brain development, which determines problem behavior later in life."

Gilbert ME - "Impact of low-level thyroid hormone disruption induced by propylthiouracil on brain development and function" Toxicol Sci 124(2):432-45 (2011) doi: 10.1093/toxsci/kfr244 ... 32/1688159

Goldman-Rakic PS, Muly EC 3rd, Williams GV - "D(1) receptors in prefrontal cells and circuits" Brain Res Rev 31(2-3):295-301 (2000) doi: 10.1016/s0165-0173(99)00045-4

Gonzalez-Nunez A, García-Solís P, Ramirez-Garcia SG, Flores-Ramirez G, Vela-Amieva M, Lara-Díaz VJ, Rojas-Martínez A - "High Iodine Urinary Concentration Is Associated with High TSH Levels but Not with Nutrition Status in Schoolchildren of Northeastern Mexico" Nutrients 13(11):3975 (2021)
Excessive iodine intake (>300 mg/L) in Mexican children: "We found a median UIC of 442 mg/L and a significant association between UIC and TSH levels by logistic regression when data were adjusted for (1) age and sex; (2) age, sex, and WC; and (3) age, sex, and weight status. ...The UIC showed a positive and significant correlation between TSH levels in the three models evaluated."

Goodman CV, Bashash M, Green R, Song P, Peterson KE, Schnaas L, Mercado-García A, Martínez-Medina S, Hernández-Avila M, Martinez-Mier A, Téllez-Rojo MM, Hu H, Till C - "Domain-specific effects of prenatal fluoride exposure on child IQ at 4, 5, and 6-12 years in the ELEMENT cohort" Environ Res 211:112993 (2022) doi: 10.1016/j.envres.2022.112993 ELEMENT ... 5122003206
NOTE: Again, no consideration at all was given to thyroid status and iodine intake in mothers or children. (Iodine intake is deemed excessive in at least a third of Mexican children at ages specified.) Also, see communication Schuld/York (11/2021)

Goodman CV, Hall M, Green R, Chevrier J, Ayotte P, Matinez-Mier EA, McGuckin T, Krzeczkowski J, Flora D, Hornung R, Lanphear B, Till C - "Iodine Status Modifies the Association between Fluoride Exposure in Pregnancy and Preschool Boys’ Intelligence" Nutrients 14(14):2920 (2022) MIREC
See extensive PFPC Commentary in PFPC Members forum: viewtopic.php?f=104&t=5008
Note: Iodine supplement use by the mothers and its implications was first brought to the attention of Goodman, then other various York team members in November 2021. See Communication Schuld/Goodman; Schuld/York Nov. 2021)
  • SEE incorrect "adequate" designation, as well as obvious MUIC/Cre correlation with IQ.
Goodman CV, Hall M, Green R, Chevrier J, Ayotte P, Martinez-Mier EA, McGuckin T, Krzeczkowski J, Flora D, Hornung R, Lanphear B, Till C - "Iodine Modifies the Effect of Fluoride Exposure in Pregnancy on Preschool Boys’ Intelligence" POSTER (2021) MIREC ... nd-MUF.pdf

Goodman CV, Till C, Green R, El-Sabbagh J, Arbuckle TE, Hornung R, Lanphear B, Seguin JR, Booij L, Fisher M, Muckle G, Bouchard MF, Ashley-Martin J - "Prenatal exposure to legacy PFAS and neurodevelopment in preschool-aged Canadian children: The MIREC cohort" Neurotoxicol Teratol 98:107181 (2023) doi: 10.1016/ MIREC ... 6223000314
"Specifically, every doubling of PFOA, PFOS, and or PFHxS was inversely associated with performance IQ, but only in males..."
NOTE: iodine intake - again - not accounted for; fluoride not(!) accounted for.[/i]
More Comments (Rob J): viewtopic.php?p=6163#p6163

Gounden V, Bhatt H, Jialal I - "Renal Function Tests" [Updated 2022 Jul 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from:

Gowachirapant S, Jaiswal N, Melse-Boonstra A, Galetti V, Stinca S, Mackenzie I, Thomas S, Thomas T, Winichagoon P, Srinivasan K, Zimmermann MB - "Effect of iodine supplementation in pregnant women on child neurodevelopment: a randomised, double-blind, placebo-controlled trial" Lancet Diabetes Endocrinol 5(11):853-863 (2017). doi: 10.1016/S2213-8587(17)30332-7

Grandjean P, Hu H, Till C, Green R, Bashash M, Flora D, Tellez-Rojo MM, Song PXK, Lanphear B, Budtz-Jørgensen E - "A Benchmark Dose Analysis for Maternal Pregnancy Urine-Fluoride and IQ in Children" Risk Anal 42(3):439-449 (2022) doi: 10.1111/risa.13767 MIREC ELEMENT
NOTE: Thyroid/Iodine status was never considered in this analysis, neither in mothers nor in the children.

Grandjean P, Meddis A, Nielsen F, Beck IH, Bilenberg N, Goodman CV, Hu H, Till C, Budtz-Jørgensen E - "Dose dependence of prenatal fluoride exposure associations with cognitive performance at school age in three prospective studies" Eur J Public Health. 2023 Oct 5:ckad170 (2023). doi: 10.1093/eurpub/ckad170. Epub ahead of print MIREC ELEMENT ODENSE - OCC ... 70/7291347
""A doubling in maternal fluoride concentration led to a slight decrease of 0.04 FSIQ points in girls and a small increase of 0.20 points in boys, but the interaction between sex and fluoride exposure was marginal...In the OCC study, we did not find evidence of fluoride neurotoxicity at low maternal U-F concentrations in the third trimester...A possible negative association could not be confirmed within the exposures measured in the OCC...Although the fluoride association was not statistically significant in the OCC cohort by itself, the joint association was significant when combined with information from the other two cohorts."
In this questionable study, results form the Odense Child Cohort - which showed an increase in IQ in boys at levels comparable to MIREC/ELEMENT - are lumped together with MIREC/ELEMENT data to show (prove?) fluoride effects at low doses on IQ. This is entirely inappropriate. No effort was made to account for excessive iodine consumption in MIREC studies. Denmark does NOT have the same iodine/supplementation problem as Canada (MIREC). Median UIC in pregnant women in Denmark at time of study was 116 ug/Cr (see Knøsgaard et al., 2023), while in MIREC women it was 153% higher, namely 294 ug/Cr.

Green R, Lanphear B, Hornung R, Flora D, Martinez-Mier EA, Neufeld R, Ayotte P, Muckle G, Till C - "Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada" JAMA Pediatr 173(10):940-948 (2019) doi: 10.1001/jamapediatrics.2019.1729 MIREC ... le/2748634
NOTE: Deemed "high-quality" by NTP. This study did not disclose any info on - nor did account for - the use of iodine supplements (88% of women -->rapid chronic iodine intake), the important "more-than-adequate" iodine issue, the mothers with treated/untreated hypo/hyperthyroidism, or the mothers taking thyroid medication ---> all major factors now identified. [Some of the authors were well aware of the fluoride-iodine issue, having published a paper on it in the previous year (Malin et al., 2018).] As in later studies, the team never considered the thyroid status/iodine intake in the 3-4-year-old children investigated, most of whom - in Canada - have more-than-adequate or excessive iodine intake, which by itself is associated with loss of IQ (i.e. Li., et al. 2022; Cui et al., 2020).
--> SEE: viewtopic.php?f=97&t=3745


Green R, Farmus L, Lanphear B, Martinez-Mier E, Flora D, Ayotte P, Till C - "Water fluoride levels and hypothyroidism in a Canadian pregnancy cohort" Abstract in: Neurotoxicol Teratol 79:106885 (2020) doi: 10.1016/ MIREC
NOTE: This is only an abstract, and related to the Hall paper from 2023, as well as Hall's poster from 2021. Here, Green et al. compare 51 women with hypothyroidism - most of whom were on thyroid medication (T4) - to 1276 controls. Again, the high intake of iodine is not accounted for - 88% of the pregnant women also took prenatal supplements containing approx. 220 µg of potassium iodide (170 I). Any increase in hypothyroidism here is likely associated with the rapid chronic increase in iodine consumption - and not the relatively small amounts of fluoride [see the many references on this list ---> i.e. Wang et al., 2022; Shi et al., 2015; Alsayed et al., 2009; Corcino et al., 2019; Kim et al., 2019; Sang et al., 2012; Shresta et al., 2017; Zhang et al., 2022; Laurberg et al., 2010; Yang et al., 2020]. This is further reflected in the high levels of antibodies, and T4 levels - both associated with more-than-adequate iodine intake [T4 and TPOab can be observed in the other posters/publications -> Hall, 2021, Goodman 2021; Hall, 2023]. Fluoride may play a modifying role, but it is certainly not the main concern at the fluoride and iodine levels, and time frame, indicated.
Of further interest: a) Here, only data from 51 women are used, while in Hall 2023 the number is given as 78 for those women with primary hypothyroidism who took thyroid medication. Why was only data from 51 pregnant women used? (There are more conflicts regarding the numbers of women with primary hypothyroidism in the Hall 2023 paper, as well as the Hall 2021 poster ---> in the 2023 paper, number of women is given as either 79 or 59, in the poster as 58; see FAQ)
b) Where is the high number of controls (1276) coming from, presuming controls are those who are euthyroid? Hall's 2023 numbers are 945 (Euthyroid, Water Fluoride + Thyroid Status) and 857 (Euthyroid, Fluoride Intake & Thyroid Status). c) How many of the 51 women in Green's study were on thyroid medication, and how many of them also took prenatal multivitamins? d) How many months/years before the first-trimester exam had the diagnosis of hypothyroidism been made? Diagnosis made in the same location? See further discussions in the forum.

Griebel-Thompson AK, Sands S, Chollet-Hinton L, Christifano D, Sullivan DK, Hull H, Carlson SE - "A scoping review of iodine and fluoride in pregnancy in relation to maternal thyroid function and offspring neurodevelopment" Advances in Nutrition Pre-print, 2023,

Guan H, Li C, Li Y, Fan C, Teng Y, Shan Z, Teng W - "High iodine intake is a risk factor of post-partum thyroiditis: result of a survey from Shenyang, Chin" J Endocrinol Invest 28(10):876-81 (2005) doi: 10.1007/BF03345318
"The median urinary iodine (MUI) of patients with PPT was significantly higher than that of healthy women (231.93 vs 199.88 microg/l p=0.00153). Pregnant women with high iodine intake had more risk of developing PPT when compared with those with low iodine intake (RR=2.92, 95%CI 1.31-6.50). We concluded that positive TPOAb was of value for predicting the occurrence and severity of PPT, and a high iodine intake was a risk factor triggering PPT."
  • Image
  • Image
Guclu F, Ozmen B, Kirmaz C, Kafesciler SO, Degirmenci PB, Taneli F, Hekimsoy Z - "Down-regulation of the auto-aggressive processes in patients with hypothyroid Hashimoto's thyroiditis following substitutive treatment with L-thyroxine" Eur Cytokine Netw 20(1):27-32 (2009) doi: 10.1684/ecn.2009.0147 ... icle.phtml

Gulinaizer A, Huang J, Tian R, Bai J, Aihemaiti A, Gao Z, Ma Y - "Effects of excessive iodine during pregnancy on thyroid function and ultrastructure of cerebral cortex in offspring rats" Environmental Hygiene 13(1):48-53 (2023) ... ?id=287149
https://bowencaibian.oss-cn-beijing.ali ... %8A%9B.pdf
"Excessive iodine intake can affect the thyroid function of offspring rats, and mild iodine excess and severe iodine excess during pregnancy can cause pathological damage to the cerebral cortex of offspring rats, thereby affecting the brain development and function of offspring."

Guo X, Shan Z, Teng W - "Experimental study on the effect of excessive fluoride and iodine fluoride on thyroid function and morphology" Chin J Intern Med 45(10):845-846 (2006)
"The influence of excessive fluoride is related to the iodine nutrition status of the body: in normal iodine nutrition conditions
excess fluoride can seriously damage thyroid cells; under iodine excess nutrition, the damage caused by high iodine is the main one."

Hall M, Lanphear B, Chevrier J, Hornung R, Green R, Goodman C, Ayotte P, Esperanza Angeles Martinez-Mier EA, Zoeller RT, Christine Till - "Fluoride exposure and hypothyroidism in a Canadian pregnancy cohort" Science of The Total Environment 869 (April 15, 2023)161149 Available online 9 February 2023, 161149 MIREC ... 9722082523
[Note: All comments made re Goodman et al, 2022 apply here as well. The York team had been informed about the issue of high iodine intake from supplements and UIC >250 ug/L (WHO "more-than-adequate" category) being strongly associated with hypothyroidism, in Nov 2021. Yet it was entirely disregarded in both studies. Not only that, Goodman et al. even came up with their own "adequate" range of UIC/cr 200-600 μg/g]. Average iodine intake reported here as being 444 μg/day, WHO recommendation is 250 μg/day.
    1) Discrepancies in TSH numbers compared to Hall poster from 2021 (next reference):
    2023 Study: TSH in primary hypothyroid women (n=78; µIU/mL; M ± SD): 3.2 (2.8)
    2021 Poster: TSH in primary hypothyroid women (n=58 (?); µIU/mL; M ± SD): 1.65 (1.04)
    2) Discrepancies in TT4 numbers compared to Hall poster from 2021 (next reference):
    2023 Study: TT4 in primary hypothyroid women (n=78; ng/mL; M ± SD): 109.3 (26.6)
    2021 Poster: TT4 in primary hypothyroid women (n= 58 (?); ng/mL; M ± SD): 118.66 (±25.23)

    There are yet more discrepancies - see TG and TPO
Hall M, Green R, Goodman CV, Farmus L, Lanphear B, Martinez-Mier EA, Hornung R, Ayotte P, Till C - "Fluoride exposure and hypothyroidism in a Canadian pregnancy cohort" (Poster, 2021) MIREC ... others.pdf
TSH in hypothyroid group (µIU/mL; M ± SD): 1.65 (±1.04)
Total T4 in hypothyroid group: (ng/mL; M ± SD) 118.66 (±25.23)
(see above)

Hall R, Lazarus JH - "Changing iodine intake and the effect on thyroid disease" Br Med J (Clin Res Ed) 294(6574):721-2 (1987) doi: 10.1136/bmj.294.6574.721

Hernandez A, Martinez ME, Ng L, Forrest D - "Thyroid Hormone Deiodinases: Dynamic Switches in Developmental Transitions" Endocrinology 162(8):bqab091 (2021) doi: 10.1210/endocr/bqab091

Hong FG, Cao YX, Yang D, Wang H - "Research on the effects of fluoride on child intellectual development under different environmental conditions" Chin Prim Health Care 15(3): 56-57 (2001)
"When fluoride and iodine not meeting national standards for drinking water are present in the same area and ingested together, the harmful effects of fluoride are more pronounced, and the resulting damage compounded. However, the damage caused independently by either high or low iodine is greater than that caused by fluoride."

Ibarluzea J, Gallastegi M, Santa-Marina L, Jiménez Zabala A, Arranz E, Molinuevo A, Lopez-Espinosa MJ, Ballester F, Villanueva CM, Riano I, Sunyer J, Tardon A, Lertxundi A - "Prenatal exposure to fluoride and neuropsychological development in early childhood: 1-to 4 years old children" Environ Res. 112181 (2021) INMA ... 5121014821
[See extensive PFPC member forum on Gipuzkoa, including history and discussion of findings: viewforum.php?f=103 ]

Ibarluzea J, Subiza-Pérez M, Arregi A, Molinuevo A, Arranz-Freijo E, de Miguel MS, Jiménez A, Andiarena A, Santa-Marina L, Lertxundi A - "Association of maternal prenatal urinary fluoride levels with ADHD symptoms in childhood" Environ Res. 2023 Jul 19:116705. doi: 10.1016/j.envres.2023.116705. Epub ahead of print. INMA ... 5123015098}
"Higher levels of MUFcr in pregnant women were associated with a lower risk of cognitive problems-inattention at 11 years. These findings are inconsistent with those from previous studies and indicate the need for other population-based studies to confirm or overturn these results."
[Gipuzkoa => 97% of women took specific iodine supplements. See: ADHD and Iodine: viewtopic.php?f=7&t=5277&p=6075 ]

Induswe B, Opiniya G, Khasakhala LI, Owino R - "The Intellectual Efficiency of Adolescents Aged 13-15- Years-Old Using Drinking Water with Varying Fluoride Concentrations in Kajiado North Sub County, Kajiado County" American Journal of Medicine and Medical Sciences 8(1):295-311 (2018)
(Only fluoride water considered, not UF)

Institute of Medicine - "Dietary reference intakes for vitamin A, vitamin K, arsenic, boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and zinc" Washington (DC): National Academies Press p. 258–89 (2001)
NOTE: In 2001, the Nutritionists at the US Institute of Medicine set the tolerable upper limit of iodine to 1100 ug/day, claiming that "no altered susceptibility of pregnant or lactating women to excess iodine has been noted". In fact, there are hundreds, if not thousands, of studies documenting increased susceptibility to excessive iodine consumption in pregnant women. A few are listed on this page. The IOM also set the UL of fluoride at an incredible 10 mg/day for pregnant women.
  • The UL is defined as "the maximum level of total chronic daily intake of a nutrient judged to be likely to pose no risk of adverse health effects to the most sensitive members of the healthy population."
Jaiswal N, Melse-Boonstra A, Sharma SK, Srinivasan K, Zimmermann MB - "The iodized salt programme in Bangalore, India provides adequate iodine intakes in pregnant women and more-than-adequate iodine intakes in their children" Public Health Nutr 18(3):403-13 (2015) doi: 10.1017/S136898001400055X ... 16AE599433
"In this selected urban population of southern India, the iodized salt programme provides adequate iodine to women throughout pregnancy, at the expense of higher iodine intake in their children."

Jastrzębska H, Kochman M, Bartoszewicz Z, Ołtarzewski M, Dębski R, Zgliczyński W - "Iodine supplementation during pregnancy of hypothyroid women treated with L-thyroxine neither influences neonatal TSH nor prevents decrease in maternal free thyroid hormone concentrations in second and third trimesters" Endokrynol Pol 67(4):367-74 (2016) doi: 10.5603/EP.a2016.0049 ... view/43562
"Median neonate TSH concentration in both groups was within normal range, but was 33% higher in the 'thyroxine + iodine' than in the 'thyroxine' group (1.91 mU/L vs. 1.34 mU/L). Moreover, 8.77% of newborns in the 'thyroxine + iodine' group had TSH > 5 mIU/L....fT4 level was lower in the third trimester in the 'thyroxine + iodine' group...The newborn TSH concentration above 5 mIU/L was found in five neonates (5.11, 5.33, 5.66, 7.38, and 9.26 mU/L, respectively). Interestingly, all of those children were from mothers of the 'thyroxine + iodine' group (5/57 = 8.77%), who were treated because of overt hypothyroidism (four of them due to Hashimoto’s thyroiditis and one— after strumectomy propter nodular goitre) (Table II)." NOTE: 72.9% of the "primary hypothyroid" women in the Hall study were on thyroid medication for hypothyroidism (Levothyroxine) - in addition to taking iodine-containing supplements.

Jensen RC, Glintborg D, Timmermann CAG, Nielsen F, Boye H, Madsen JB, Bilenberg N, Grandjean P, Jensen TK, Andersen MS - "Higher free thyroxine associated with PFAS exposure in first trimester. The Odense Child Cohort" Environ Res 212(Pt D):113492 (2022). doi: 10.1016/j.envres.2022.113492. ODENSE - OCC ... 5122008192

Jiang Y, Guo X, Sun Q, Shan Z, Teng W - "Effects of Excess Fluoride and Iodide on Thyroid Function and Morphology" Biol Trace Elem Res 170(2):382-38 (2015) ... 015-0479-0 ... f=7&t=1459
"The damage to follicular epithelial cells upon fluoride or iodide treatment was easily observed by transmission electron microscopy, but the effects were most dramatic upon treatment with both fluoride and iodide. These results suggest that iodide causes the most damage but that fluoride can promote specific changes in the function and morphology of the thyroid, either alone or in combination with iodide."

Jin M, Zhang Z, Li Y, Teng D, Shi X, Ba J, Chen B, Du J, He L, Lai X, Teng X, Li Y, Chi H, Liao E, Liu C, Liu L, Qin G, Qin Y, Quan H, Shi B, Sun H, Tang X, Tong N, Wang G, Zhang JA, Wang Y, Xue Y, Yan L, Yang J, Yang L, Yao Y, Ye Z, Zhang Q, Zhang L, Zhu J, Zhu M, Ning G, Mu Y, Zhao J, Teng W, Shan Z - "U-Shaped Associations Between Urinary Iodine Concentration and the Prevalence of Metabolic Disorders: A Cross-Sectional Study" Thyroid 30(7):1053-1065 (2020) doi: 10.1089/thy.2019.0516
"The association between UICs in adults and metabolic disorders and its related diseases is U-shaped. The association between UIC and metabolic disorders disappears in cases of iodine deficiency (<100 μg/L) or excess (≥500 μg/L)."

Juan W, Trumbo PR, Spungen JH, Dwyer JT, Carriquiry AL, Zimmerman TP, Swanson CA, Murphy SP - "Comparison of 2 methods for estimating the prevalences of inadequate and excessive iodine intakes" Am J Clin Nutr 104 Suppl 3(Suppl 3):888S-97S (2016) ... 8S/4564248
Similarly to Canadian children, 40% of US children between the ages of 6 and 8 now have excessive iodine intake. The rates are higher for boys than girls.

Kämpe O, Jansson R, Karlsson FA - "Effects of L-thyroxine and iodide on the development of autoimmune postpartum thyroiditis" J Clin Endocrinol Metab 70(4):1014-8 (1990) doi: 10.1210/jcem-70-4-1014

Kalarani IB, Veerabathiran R - "Impact of iodine intake on the pathogenesis of autoimmune thyroid disease in children and adults" Ann Pediatr Endocrinol Metab 27(4):256-264 I (2022) doi: 10.6065/apem.2244186.093
"Excessive iodine intake is a risk factor for thyroid diseases, including AITD, and certain people are more susceptible, including the elderly, pregnant women, fetuses, and neonates, as well as those with pre-existing goiters or iodine deficiency. Either a deficit or excess of iodine may increase the incidence of thyroid disease, and iodine intakes should be maintained within a limited optimal range."

Kampouri M, Gustin K, Stråvik M, Barman M, Levi M, Daraki V, Jacobsson B, Sandin A, Sandberg AS, Wold AE, Vahter M, Kippler M - "Association of maternal urinary fluoride concentrations during pregnancy with size at birth and the potential mediation effect by maternal thyroid hormones: The Swedish NICE birth cohort" Environ Res 214(Pt 4):114129 (2022). doi: 10.1016/j.envres.2022.114129114129 ... 5122014566
PFPC Commentary: viewtopic.php?p=5767#p5767

Kampouri M, Margetaki K, Koutra K, Kyriklaki A, Karakosta P, Anousaki D, Chalkiadaki G, Vafeiadi M, Kogevinas M, Chatzi L - "Maternal mild thyroid dysfunction and offspring cognitive and motor development from infancy to childhood: the Rhea mother-child cohort study in Crete, Greece" J Epidemiol Community Health 75(1):29-35 (2021)
"Maternal thyroid autoimmunity is associated with decreased offspring perceptual performance and motor ability and increased risk for adverse non-verbal cognitive development from infancy to childhood."

Kang MJ, Hwang IT, Chung HR - "Excessive Iodine Intake and Subclinical Hypothyroidism in Children and Adolescents Aged 6-19 Years: Results of the Sixth Korean National Health and Nutrition Examination Survey, 2013-2015" Thyroid 28(6):773-779 (2018) doi: 10.1089/thy.2017.0507
"The prevalence of SCH was significantly higher in the iodine deficient and iodine excess groups compared to those in the UIC 100-299.9 μg/L group (p = 0.038). Therefore, there was a U-shaped and inverted U-shaped correlation between serum levels of TSH and fT4 with UIC, respectively."

Karbownik-Lewińska M, Stępniak J, Iwan P, Lewiński A - "Iodine as a potential endocrine disruptor-a role of oxidative stress" Endocrine 78(2):219-240 (2022) doi: 10.1007/s12020-022-03107-7

Kalarani IB, Veerabathiran R - "Impact of iodine intake on the pathogenesis of autoimmune thyroid disease in children and adults" Ann Pediatr Endocrinol Metab 27(4):256-264 (2022) doi: 10.6065/apem.2244186.093
"Excessive iodine intake is a risk factor for thyroid diseases, including AITD, and certain people are more susceptible, including the elderly, pregnant women, fetuses, and neonates, as well as those with pre-existing goiters or iodine deficiency. Either a deficit or excess of iodine may increase the incidence of thyroid disease, and iodine intakes should be maintained within a limited optimal range."

Katz PM, Leung AM, Braverman LE, Pearce EN, Tomlinson G, He X, Vertes J, Okun N, Walfish PG, Feig DS - "Iodine nutrition during pregnancy in Toronto, Canada" Endocr Pract 19(2):206-11 (2013) doi: 10.4158/EP12193.OR. ... 20)40458-6

Khandare AL, Gourineni SR, Validandi V - "Dental fluorosis, nutritional status, kidney damage, and thyroid function along with bone metabolic indicators in school-going children living in fluoride-affected hilly areas of Doda district, Jammu and Kashmir, India" Environ Monit Assess 189: 579 (2017) ... 017-6288-5 ... f=3&t=1722

Kheradpisheh Z, Mirzaei M, Mahvi AH, Mokhtari M, Azizi R, Fallahzadeh H, Ehrampoush MH - "Impact of Drinking Water Fluoride on Human Thyroid Hormones: A Case-Control Study" Scientific Reports Volume 8, Article number: 2674 (2018) ... 1737#p1737

Kim HI, Oh HK, Park SY, Jang HW, Shin MH, Han JM, Bae JC, Kim SW, Kim TH, Chung JH - "Non-immune-related hypothyroidism and its relationship with excess iodine" Eur J Nutr 58(7):2851-2858 (2019)
"In the TPO Ab negative population, the prevalence of hypothyroidism was increased significantly in the subgroup with UIC between 250 and 749 µg/L (HR 2.12 [1.17, 3.83]) and ≥ 750 µg/L (HR 3.42 [1.93, 6.04]) or the subgroups with estimated iodine intake ≥ 750 µg/day (HR 2.81 [1.64, 4.80]). This nationwide study demonstrated that most cases of hypothyroidism in iodine-sufficient areas are non-immune-related and are associated with excess iodine above a certain level. More attention to this unrecognized but widespread potential health risk is needed...Because many cases of iodine-induced hypothyroidism are reversible by iodine restriction without T4 replacement, modest iodine restriction might be considered before T4 replacement as a treatment option for subclinical hypothyroidism in iodine-sufficient areas."
Among 233 subjects with hypothyroidism, 130 (55.8%) had non-immune-related hypothyroidism with UIC ≥ 250 μg/L.

Klubo-Gwiezdzinska J, Burman KD, Van Nostrand D, Wartofsky L - "Levothyroxine treatment in pregnancy: indications, efficacy, and therapeutic regimen" J Thyroid Res 2011:843591 (2011)doi: 10.4061/2011/843591

Knøsgaard L, Andersen S, Hansen AB, Sørensen A, Vestergaard P, Andersen SL - "Iodine status in Danish pregnant women after an increase in iodine fortification" Clin Endocrinol (Oxf) 98(3):407-414 (2023) doi: 10.1111/cen.14797

Knudsen N, Bülow I, Jørgensen T, Perrild H, Ovesen L, Laurberg P - “Serum Tg--a sensitive marker of thyroid abnormalities and iodine deficiency in epidemiological studies” J Clin Endocrinol Metab 86(8):3599-603 (2001) doi: 10.1210/jcem.86.8.7772

Konno N, Makita H, Yuri K, Iizuka N, Kawasaki K - "Association between dietary iodine intake and prevalence of subclinical hypothyroidism in the coastal regions of Japan" J Clin Endocrinol Metab 78(2):393-7 (1994) doi: 10.1210/jcem.78.2.8106628 ... 93/2655500
"These results indicate that 1) the prevalence of hypothyroidism in iodine sufficient areas may be associated with the amount of iodine ingested; 2) hypothyroidism is more prevalent and marked in subjects consuming further excessive amounts of iodine; and 3) excessive intake of iodine should be considered an etiology of hypothyroidism in addition to chronic thyroiditis in these areas."

Korevaar TI, Muetzel R, Medici M, Chaker L, Jaddoe VW, de Rijke YB, Steegers EA, Visser TJ, White T, Tiemeier H, Peeters RP - "Association of maternal thyroid function during early pregnancy with offspring IQ and brain morphology in childhood: a population-based prospective cohort study" Lancet Diabetes Endocrinol 4(1):35-43 (2016)
"Both low and high maternal free thyroxine concentrations during pregnancy were associated with lower child IQ and lower grey matter and cortex volume. The association between high maternal free thyroxine and low child IQ suggests that levothyroxine therapy during pregnancy, which is often initiated in women with subclinical hypothyroidism during pregnancy, might carry the potential risk of adverse child neurodevelopment outcomes when the aim of treatment is to achieve high-normal thyroid function test results."
NOTE: 72.9% of the "primary hypothyroid" women in the Hall study were on thyroid medication for hypothyroidism (Levothyroxine - T4) - in addition to taking iodine-containing supplements. SEE: Table 1: ... 2523#t0005

Krzeczkowski JE, Hall M, McGuckin T, Lanphear B, Bertinato J, Ayotte P, Chevrier J, Goodman C, Green R, Till C - “Iodine status in a large Canadian pregnancy cohort” Am J Obstet Gynecol MFM 5(1):100784 I(2023) doi: 10.1016/j.ajogmf.2022.100784 MIREC ... 22)00214-2

Kuzmenko NV, Tsyrlin VA, Pliss MG, Galagudza MM - "Seasonal variations in levels of human thyroid-stimulating hormone and thyroid hormones: a meta-analysis" Chronobiol Int 38(3):301-317 (2021) doi: 10.1080/07420528.2020.1865394 ... 20.1865394
"We found that circulating TSH levels were higher in winter than in other seasons, and FT4 levels were higher in autumn than in winter. T4 level had no pronounced seasonal dynamics. The level of circulating T3 was significantly higher in winter than in summer and FT3 levels were lower in summer than in autumn and spring. In addition, analysis of TSH seasonal dynamics (winter vs summer) accounting for gender differences showed pronounced increases in TSH levels during winter in women, but not in men; and also significant increases in FT4 levels during summer in men, but not in women."

Laurberg P, Andersen S, Bjarnadóttir RI, Carlé A, Hreidarsson A, Knudsen N, Ovesen L, Pedersen I, Rasmussen L - "Evaluating iodine deficiency in pregnant women and young infants-complex physiology with a risk of misinterpretation" Public Health Nutr 10(12A):1547-52 (2007) discussion 1553. doi: 10.1017/S1368980007360898 ... 8C843CEBFF

Laurberg P, Cerqueira C, Ovesen L, Rasmussen LB, Perrild H, Andersen S, Pedersen IB, Carlé A - "Iodine intake as a determinant of thyroid disorders in populations" Best Pract Res Clin Endocrinol Metab 24(1):13-27 (2010) doi: 10.1016/j.beem.2009.08.013 ... 0X09001006
"Even minor differences in iodine intake between populations are associated with differences in the occurrence of thyroid disorders. Both iodine intake levels below and above the recommended interval are associated with an increase in the risk of disease in the population. Optimally, iodine intake of a population should be kept within a relatively narrow interval where iodine deficiency disorders are prevented, but not higher."

Laurberg P, Pedersen I, Carle A, Andersen S, Knudsen N, Ovesen L, Rasmussen LB - "The U-shaped Curve of Iodine Intake and Thyroid Disorders" Comprehensive Handbook of Iodine, Elsevier, Amsterdam, pp. 449–455 (2009)

Lee SY, Pearce EN - "Reproductive endocrinology: Iodine intake in pregnancy--even a little excess is too much" Nat Rev Endocrinol 11(5):260-1 (2015) doi: 10.1038/nrendo.2015.28

Lee YJ, Cho SW, Lim YH, Kim BN, Kim JI, Hong YC, Park YJ, Shin CH, Lee YA - "Relationship of iodine excess with thyroid function in 6-year-old children living in an iodine-replete area" Front Endocrinol (Lausanne) 14:1099824 (2023) doi: 10.3389/fendo.2023.1099824 ... 23.1099824
"Excess iodine was prevalent (73.8%) in 6-year-old Korean children. Excess iodine was associated with a decrease in FT4 or T3 levels and an increase in TSH levels."

Leung AM, Braverman LE - "Consequences of excess iodine" Nat Rev Endocrinol 10(3):136-42 (2014) doi: 10.1038/nrendo.2013.251 ... obtype=pdf

Levie D, Korevaar TIM, Bath SC, Murcia M, Dineva M, Llop S, Espada M, van Herwaarden AE, de Rijke YB, Ibarluzea JM, Sunyer J, Tiemeier H, Rayman MP, Guxens M, Peeters RP - "Association of Maternal Iodine Status With Child IQ: A Meta-Analysis of Individual Participant Data" J Clin Endocrinol Metab 104(12):5957-5967 (2019) doi: 10.1210/jc.2018-02559 ... 57/5421020

Levie D, Derakhshan A, Shu H, Broeren MAC, de Poortere RA, Peeters RP, Bornehag CG, Demeneix B, Korevaar TIM - "The Association of Maternal Iodine Status in Early Pregnancy with Thyroid Function in the Swedish Environmental Longitudinal, Mother and Child, Asthma and Allergy Study" Thyroid 29(11):1660-16 (2019)
"TPOAb positivity is associated with a higher risk of miscarriage, preterm birth, child behavioral problems, and lower child IQ. In the current study, TPOAb positivity occurred more often in women with low or high UI/Creat...Interestingly, thyroid antibody concentrations tend to decline after the first trimester due to immune tolerance, and this could potentially affect the definition of TPOAb positivity."

Li C, Peng S, Zhang X, Xie X, Wang D, Mao J, Teng X, Shan Z, Teng W - "The Urine Iodine to Creatinine as an Optimal Index of Iodine During Pregnancy in an Iodine Adequate Area in China" J Clin Endocrinol Metab 101(3):1290-8 (2016) doi: 10.1210/jc.2015-3519 ... 90/2804950
NOTE: This much-cited study was conducted in three cities [Dalian City, Dandong City, and Shenyang City] in the Liaoning province in China, an endemic fluorosis area (Li et al., 2004; Yu et al., 2018; Liu et al., 2006). Unfortunately, this study included thousands of women from endemic fluorosis areas - yet fluoride intake was never considered in the assessment! In addition, some areas included had high I and high F intake. (The upper limit of serum TSH in the first trimester was much higher than 2.5 mIU/L - see Li et al., 2014).

Li C, Shan Z, Mao J, Wang W, Xie X, Zhou W, Li C, Xu B, Bi L, Meng T, Du J, Zhang S, Gao Z, Zhang X, Yang L, Fan C, Teng W - "Assessment of thyroid function during first-trimester pregnancy: what is the rational upper limit of serum TSH during the first trimester in Chinese pregnant women?" J Clin Endocrinol Metab 99(1):73-9 (2014) doi: 10.1210/jc.2013-1674

Li Dong, LiJu, Li Li, et al. - "Association between Urinary Iodine Levels and Sensory Integration Dysfunction in Preschool Children" Chinese General Practice 22(26):3222-3226 (2019) DOI: 10.12114/j.issn.1007-9572.2019.00.265 [Hubei province] ... 019.00.265
"Conclusion: Urinary iodine levels in preschool children may affect the SID [sensory integration dysfunction], and low-level urinary iodine may increase the risk of children's vestibular imbalance and proprioceptive dysfunction."
(The higher the UIC, the higher the SID incidence, in males more than females.)

Li F, Wan S, Zhang L, Li B, He Y, Shen H, Liu L - "A Meta-Analysis of the Effect of Iodine Excess on the Intellectual Development of Children in Areas with High Iodine Levels in their Drinking Water" Biol Trace Elem Res 200(4):1580-1590 (2022) ... 21-02801-3
"This study found that high iodine concentration was statistically significantly associated with a decline in intelligence level in children. Comparatively, the intelligence level of children who were exposed to high iodine concentrations reduced significantly by 1.64 points. These findings have public health implications."

Li J, Li Y, Shi X, Teng D, Teng X, Teng W, Shan Z; Thyroid Disorders, Iodine Status and Diabetes Epidemiological Survey Group - "Prevalence and risk factors of hypothyroidism after universal salt iodisation: a large cross-sectional study from 31 provinces of China" BMJ Open. 2023 Feb 28;13(2):e064613 (2023) doi: 10.1136/bmjopen-2022-064613
"...SCH was positively correlated with increased urine iodine concentration, but this correlation was only in antibody-negative female patients. In non-autoimmune and male populations, there was a U-shaped relationship between severe SCH and OH and urine iodine concentration." [Fluoride not investigated...]

Li Y, Teng D, Ba J, Chen B, Du J, He L, Lai X, Teng X, Shi X, Li Y, Chi H, Liao E, Liu C, Liu L, Qin G, Qin Y, Quan H, Shi B, Sun H, Tang X, Tong N, Wang G, Zhang JA, Wang Y, Xue Y, Yan L, Yang J, Yang L, Yao Y, Ye Z, Zhang Q, Zhang L, Zhu J, Zhu M, Ning G, Mu Y, Zhao J, Shan Z, Teng W - "Efficacy and Safety of Long-Term Universal Salt Iodization on Thyroid Disorders: Epidemiological Evidence from 31 Provinces of Mainland China" Thyroid 30(4):568-579 (2020). doi: 10.1089/thy.2019.0067
Increased iodine intake was significantly associated with elevated serum thyrotropin (TSH) levels. "Furthermore, the association was only found in non-autoimmune subclinical hypothyroidism (negative thyroid antibodies) but not in autoimmune subclinical hypothyroidism (positive thyroid antibodies)" | DI and EI were both associated with higher prevalence of overt hyperthyroidism resulting in a U-shaped curve.

Li Xiao, Cui Shen, Hongmei Liu, Li Xiang, Han Hepeng - "Study on the effect of fluoride content in drinking water on the hazards of high iodine" Chinese Journal of Control of Endemic Diseases (5)348-349 (2009)

Li Y, Shan Z, Teng W, Yu X, Li Y, Fan C, Teng X, Guo R, Wang H, Li J, Chen Y, Wang W, Chawinga M, Zhang L, Yang L, Zhao Y, Hua T - "Abnormalities of maternal thyroid function during pregnancy affect neuropsychological development of their children at 25-30 months" Clin Endocrinol (Oxf) 72(6):825-9 (2010). doi: 10.1111/j.1365-2265.2009.03743.x. ... 09.03743.x
"Children of women with subclinical hypothyroidism, hypothyroxinemia and elevated TPOAb titres had mean intelligence scores 8.88, 9.30 and 10.56 points lower than those of the control group ...mean motor scores were 9.98, 7.57 and 9.03 points lower than those of the controls..."

Li Y, Shan Z, Teng W; Thyroid Disorders, Iodine Status and Diabetes Epidemiological Survey Group - "The Iodine Status and Prevalence of Thyroid Disorders Among Women of Childbearing Age in China: National Cross-sectional Study" Endocr Pract 27(10):1028-1033 (2021) doi: 10.1016/j.eprac.2021.03.017 ... 5/fulltext
"19.04% and 19.87% of the participants were classified as having iodine deficiency and excessive iodine, respectively. ..14.28% had subclinical hypothyroidism, 13.53% were positive for thyroid peroxidase antibodies, and 14.55% were positive for thyroglobulin antibodies. Excessive iodine and overweight were associated with higher odds of subclinical hypothyroidism."

Lin Fa-Fu, Aihaiti, Zhao Hong-Xin, Lin Jin, Jiang Ji-Yong, Maimaiti, and Aiken - "High-fluoride and Low-iodine Environment and Subclinical Cretinism in Xinjiang" Endemic Diseases Bulletin 6(2):62-67 (1991)

Lin Fa-Fu - "A Study on the Relationship between Serum rT3 and Environmental Iodine or Fluoride Levels" Endem Dis Bull 7(2):68-70 (1992)
Notice suppression of TSH at High Iodine + High Fluoride and the rT3 increase in all instances.

Liu J, Mao C, Dong L, Kang P, Ding C, Zheng T, Wang X, Xiao Y - "Excessive Iodine Promotes Pyroptosis of Thyroid Follicular Epithelial Cells in Hashimoto's Thyroiditis Through the ROS-NF-κB-NLRP3 Pathway" Front Endocrinol (Lausanne) 10:778 (2019) doi: 10.3389/fendo.2019.00778 ... 00778/full

Liu GY, Chai CY, Kang SL - "Effects of fluoride on the activity of deiodinase in the liver of chickens" Chin J Vet Med 39:14-5 (2003)
First, fluoride causes an increase in D1, then, at 90 days, a severe decrease. Downregulation of D1 leads to an increase in circulating rT3, because the conversion of rT3 to T2 is significantly reduced, resulting in an accumulation of rT3. (Compare to timing issues in Zhao et al., 1998;1992)

Liu H, Zeng Q, Cui Y, Yu L, Zhao L, Hou C, Zhang S, Zhang L, Fu G, Liu Y, Jiang C, Chen X, Wang A - "The effects and underlying mechanism of excessive iodide on excessive fluoride-induced thyroid cytotoxicity" Environ Toxicol Pharmacol 38(1):332-40 (2014) doi: 10.1016/j.etap.2014.06.008. ... 8914001513

Liu H, Hou C, Zeng Q, Zhao L, Cui Y, Yu L, Wang L, Zhao Y, Nie J, Zhang B, Wang A - "Role of endoplasmic reticulum stress-induced apoptosis in rat thyroid toxicity caused by excess fluoride and/or iodide" Environ Toxicol Pharmacol 46:277-285 (2016) doi: 10.1016/j.etap.2016.08.007 ... 8916302083
"The combined effects of excess fluoride and iodide on follicular structure depend on the dominant element: the iodide cytotoxicity is dominant with a low fluoride concentration, while the fluoride cytotoxicity is dominant with a high fluoride concentration."

Liu Y, Chen H, Jing C, Li F - "The Association Between Maternal Subclinical Hypothyroidism and Growth, Development, and Childhood Intelligence: A Meta-analysis" J Clin Res Pediatr Endocrinol 10(2):153-161 (2018) doi: 10.4274/jcrpe.4931 ... 53_161.pdf
"Conclusion: Maternal SCH in pregnancy is associated with increased risk of adverse neonatal outcomes, including delayed intellectual and motor development, low birth weight, premature delivery, fetal distress and fetal growth restriction."

Liu HL, Lam LT, Zeng Q, Han SQ, Fu G, Hou CC - "Effects of drinking water with high iodine concentration on the intelligence of children in Tianjin, China" J Public Health (Oxf) 31(1):32-8 (2009) doi: 10.1093/pubmed/fdn097 ... 32/1586582
(Study conducted in 2005 - children born in mid 1990s)
"There was a significant association between residing in the very high water iodine region and a reduction of IQ by an average of about nine points (P = 0.022), after adjusting for the potential confounding factors."

Liu L, Wang D, Liu P, Meng F, Wen D, Jia Q, Liu J, Zhang X, Jiang P, Shen H - "The relationship between iodine nutrition and thyroid disease in lactating women with different iodine intakes" Br J Nutr 114(9):1487-95 (2015) ... 11F952186A
"The prevalence of thyroid disease in lactating women, particularly subclinical hypothyroidism, was higher in the I-excess group than in the I-sufficient group (P<0·05). In areas with excessive water I content, high thyroid peroxidase antibody and high thyroglobulin levels were risk factors for abnormal thyroid-stimulating hormone levels. Our data collectively suggest that excessive I intake potentially causes subclinical hypothyroidism in lactating women. Moreover, enhanced monitoring of I status is important to avoid adverse effects of I deficiency or excess, particularly in susceptible populations such as pregnant or lactating women and infants."

Liu X, Xiao Z, Cheng L, Jian L - "Iodine nutrition level and thyroid function in pregnant women in the Yongchuan district of Chongqing" J Clin Transl Res 8(6):516-522 (2022)
"The rate of thyroid diseases was significantly higher in subjects with more than adequate as well as excessive iodine intake cohorts compared to pregnant women with adequate iodine intake...The TSH concentration in subjects with inadequate iodine intake (UIC < 150 μg/L) was lower compared to subjects with adequate iodine intake (UIC 150 – 249 μg/L), but higher than in subjects with more than adequate intake (UIC 250 – 499 μg/L) and excess iodine intake (UIC ≥ 500 μg/L) (P < 0.05). TSH concentration and UIC were positively correlated..."

Liu Y, Téllez-Rojo M, Hu H, Sánchez BN, Martinez-Mier EA, Basu N, Mercado-García A, Solano-González M, Peterson KE - "Fluoride exposure and pubertal development in children living in Mexico City" Environ Health 18(1):26 (2019). doi: 10.1186/s12940-019-0465-7 ... 019-0465-7 ELEMENT

Lopes van Balen VA, van Gansewinkel TAG, de Haas S, Spaan JJ, Ghossein-Doha C, van Kuijk SMJ, van Drongelen J, Cornelis T, Spaanderman MEA - "Maternal kidney function during pregnancy: systematic review and meta-analysis" Ultrasound Obstet Gynecol 54(3):297-307 (2019)
"Creatinine clearance was highest at 15–21 weeks' healthy pregnancy, GFR is increased as early as the first trimester, as compared with non-pregnant values, and the kidneys continue to function at a higher rate throughout gestation."

Luo Y, Kawashima A, Ishido Y, Yoshihara A, Oda K, Hiroi N, Ito T, Ishii N, Suzuki K - "Iodine excess as an environmental risk factor for autoimmune thyroid disease" Int J Mol Sci 15(7):12895-912 (2014). doi: 10.3390/ijms150712895

Ma ZF, Venn BJ, Manning PJ, Cameron CM, Skeaff SA - “The sensitivity and specificity of thyroglobulin concentration using repeated measures of urinary iodine excretion” Eur J Nutr 57(4):1313-1320 (2018) doi: 10.1007/s00394-017-1410-6 ... 017-1410-6

Ma ZF, Skeaff SA - “Thyroglobulin as a biomarker of iodine deficiency: a review” Thyroid 24(8):1195-209 (2014) doi: 10.1089/thy.2014.0052
"Although six of eight studies (37,38,74,75,77,79) collected information on the use of iodine supplements in pregnancy, of these, only one study (37) reported that the Tg concentration of women taking iodine supplements was significantly lower compared with women who did not take supplements (i.e., difference of ∼15 μg/L). We are unaware of any published studies of pregnant women with adequate iodine status that include measures of both UIC and Tg.”

Ma R, Yan M, Han P, Wang T, Li B, Zhou S, Zheng T, Hu Y, Borthwick AGL, Zheng C, Ni J - "Deficiency and excess of groundwater iodine and their health associations" Nat Commun 13(1):7354 (2022) doi: 10.1038/s41467-022-35042-6
SEE full graph: ... /figures/4

Maitre L, Villanueva CM, Lewis MR, Ibarluzea J, Santa-Marina L, Vrijheid M, Sunyer J, Coen M, Toledano MB - "Maternal urinary metabolic signatures of fetal growth and associated clinical and environmental factors in the INMA study" BMC Med 14(1):177 (2016) doi: 10.1186/s12916-016-0706-3. INMA ... 016-0706-3

Malin AJ, Riddell J, McCague H, Till C - "Fluoride exposure and thyroid function among adults living in Canada: Effect modification by iodine status." Environ Int 121(Pt 1):667-674 (2018) doi: 10.1016/j.envint.2018.09.026 ... via%3Dihub

Mallawa Kankanamalage O, Zhou Q, Li X - “Understanding the Pathogenesis of Gestational Hypothyroidism” Front Endocrinol (Lausanne) 12:653407 (2021)doi: 10.3389/fendo.2021.653407 ... 53407/full

Markhus MW, Dahl L, Moe V, Abel MH, Brantsæter AL, Øyen J, Meltzer HM, Stormark KM, Graff IE, Smith L, Kjellevold M - "Maternal Iodine Status is Associated with Offspring Language Skills in Infancy and Toddlerhood" Nutrients 10(9):1270 (2018) doi: 10.3390/nu10091270
"Maternal use of iodine-containing supplements was associated with lower gross motor skills...The use of iodine-containing supplements was not associated with beneficial effects."

Maumené E -“Experiencé pour déterminer l’action des fluores sur l’economie animale” Compt Rend Acad Sci (Paris) 39:538-539 (1854)

MacPherson S, Arbuckle TE, Fisher M - "Adjusting urinary chemical biomarkers for hydration status during pregnancy" J Expo Sci Environ Epidemiol. 28(5):481-493 (2018) doi: 10.1038/s41370-018-0043-z.
"Based on the linear mixed model results, we found that UFR and creatinine excretion rates differed systematically across the population, with respect to body mass index (BMI) and time...This analysis showed that SG showed a slightly better within-person reproducibility and the least amount of systematic variation when compared to creatinine adjustment."

Medici M, Ghassabian A, Visser W, de Muinck Keizer-Schrama SMPF, Jaddoe VWV, Visser WE, Hooijkaas H, Hofman A, Steegers EAP, Bongers-Schokking JJ, Ross HA, Tiemeier H, Visser TJ, de Rijke YB, Peeters RP - "Women with high early pregnancy urinary iodine levels have an increased risk of hyperthyroid newborns: the population-based Generation R Study" Clin Endocrinol (Oxf) 80(4):598–606 (2014)

Moynihan M, Telléz-Rojo MM, Colacino J, Jones A, Song PXK, Cantoral A, Mercado-García A, Peterson KE - "Prenatal Cadmium Exposure Is Negatively Associated With Adiposity in Girls Not Boys During Adolescence" Front Public Health 7:61 (2019) doi: 10.3389/fpubh.2019.00061 ELEMENT ... 00061/full

Mulder TA, Korevaar TIM, Peeters RP, van Herwaarden AE, de Rijke YB, White T, Tiemeier H - "Urinary Iodine Concentrations in Pregnant Women and Offspring Brain Morphology" Thyroid 31(6):964-972 (2021) doi: 10.1089/thy.2020.0582
Note the bi-phasic effects on grey matter. Compare to T4 data in Korevaar et al., 2016.
"In sensitivity analyses using the UI/Creat categories based on the WHO categorization for UIC values, both low and high UI/Creat across pregnancy were associated with smaller total gray matter volume when considering UI/Creat 150–249 μg/g as the reference category (β [CI]: −14.7 [−23.8 to −5.7] and −13.0 [−20.6 to −5.5], respectively) (Table 4)."

Mullan K, McMullan P, Kayes L, McCance D, Hunter A, Woodside JV - “Thyroglobulin levels among iodine deficient pregnant women living in Northern Ireland” Eur J Clin Nutr 76(11):1542-1547 (2022) doi: 10.1038/s41430-022-01144-z

Mumm H, Dreyer AF, Bleses D, Glintborg D, Jensen TK, Boye H, Trecca F, Andersen M - "Maternal cortisol levels in 3rd trimester and early language development, a study of 1,093 mother-child pairs from Odense Child Cohort". ODENSE - OCC
Endocrine Abstracts (2023) 90 P449 | DOI: 10.1530/endoabs.90.P449.
"Higher 3rd trimester maternal cortisol levels showed a positive association with development of productive vocabulary in boys at age 12-21 months and age 22-37 months...Higher maternal cortisol levels in 3rd trimester were positively associated with receptive vocabulary in girls at 12-21 months-of-age."

Murcia M, Rebagliato M, Espada M, Vioque J, Santa Marina L, Alvarez-Pedrerol M, Lopez-Espinosa MJ, León G, Iñiguez C, Basterrechea M, Guxens M, Lertxundi A, Perales A, Ballester F, Sunyer J; INMA Study Group - "Iodine intake in a population of pregnant women: INMA mother and child cohort study, Spain" J Epidemiol Community Health 64(12):1094-9 (2010) doi: 10.1136/jech.2009.092593 INMA

Murcia M, Rebagliato M, Iñiguez C, Lopez-Espinosa MJ, Estarlich M, Plaza B, Barona-Vilar C, Espada M, Vioque J, Ballester F - "Effect of iodine supplementation during pregnancy on infant neurodevelopment at 1 year of age" Am J Epidemiol 173(7):804-12 (2011)
doi: 10.1093/aje/kwq424 INMA
"Maternal intake of ≥150 μg/day, compared with <100 μg/day, of iodine from supplements was associated with a 5.2-point decrease in PDI (95% confidence interval: -8.1, -2.2) and a 1.8-fold increase in the odds of a PDI <85 (95% confidence interval: 1.0, 3.3). When analyses were stratified by sex, this association was intensified for girls but was not observed for boys."

Næss S, Aakre I, Strand TA, Dahl L, Kjellevold M, Stokland AM, Nedrebø BG, Markhus MW - "Infant iodine status and associations with maternal iodine nutrition, breast-feeding status and thyroid function" Br J Nutr 129(5):854-863 (2023) doi: 10.1017/S0007114522001465
"Breastfed infants had lower median UIC compared with formula-fed infants at ages 3 months (76 v. 190 µg/l) and 6 months (105 v. 315 µg/l)."

Nazarpour S, Ramezani Tehrani F, Rahmati M, Azizi F - "Prediction of preterm delivery based on thyroid peroxidase antibody levels and other identified risk factors" Eur J Obstet Gynecol Reprod Biol 284:125-130 (2023) doi: 10.1016/j.ejogrb.2023.03.025 ... 23)00116-1 [see also: Xu et al., 2023]
"A combination of T4, TPOAb, and previous preterm delivery was identified as independent risk factors that accurately predicted preterm delivery. The total score obtained based on the nomogram designed based on risk factors can predict the risk of preterm delivery."

Newman DJ, Pugia MJ, Lott JA, Wallace JF, Hiar AM - "Urinary protein and albumin excretion corrected by creatinine and specific gravity" Clin Chim Acta 294(1-2):139-55 (2000) doi: 10.1016/s0009-8981(00)00181-9 ... 8100001819

Päkkilä F, Männistö T, Hartikainen AL, Ruokonen A, Surcel HM, Bloigu A, Vääräsmäki M, Järvelin MR, Moilanen I, Suvanto E - "Maternal and Child's Thyroid Function and Child's Intellect and Scholastic Performance" Thyroid 25(12):1363-74 (2015) doi: 10.1089/thy.2015.0197

Päkkilä F, Männistö T, Pouta A, Hartikainen AL, Ruokonen A, Surcel HM, Bloigu A, Vääräsmäki M, Järvelin MR, Moilanen I, Suvanto E - "The impact of gestational thyroid hormone concentrations on ADHD symptoms of the child" J Clin Endocrinol Metab 99(1):E1-8 (2014) doi: 10.1210/jc.2013-2943. Epub 2013 Dec 11. PMID: 24384024; PMCID: PMC3879664
"Overall, boys had higher prevalence of ADHD symptoms, Rutter B2 scores of 9 or greater, and combined ADHD symptoms than girls....The prevalence of both inattention and hyperactivity were slightly higher in boys than girls, being in line with previous data."

Park S, Lee SM, Park JS, Hong JS, Chin HJ, Na KY, Kim DK, Oh KH, Joo KW, Kim YS, Lee H - "Midterm eGFR and Adverse Pregnancy Outcomes: The Clinical Significance of Gestational Hyperfiltration" Clin J Am Soc Nephrol 12(7):1048-1056 (2017) doi: 10.2215/CJN.12101116
"Data from 1931 pregnancies were included. The relationship between midterm eGFR and adverse pregnancy outcomes, which occurred in 538 mothers, was defined by a nonlinear U-shaped curve."

Pearce EN - "Diagnosis and management of thyrotoxicosis" BMJ 332(7554):1369-73 (2006) doi: 10.1136/bmj.332.7554.1369

Pecina J, Garrison GM, Bernard ME - "Levothyroxine dosage is associated with stability of thyroid-stimulating hormone values" Am J Med 127(3):240-5 (2014) doi: 10.1016/j.amjmed.2013.11.012 ... 8/fulltext

Pedersen IB, Knudsen N, Carle A, Vejbjerg P, Jorgensen T, Perrild H, Ovesen L, Rasmussen LB, Laurberg P - “A cautious iodization programme bringing iodine intake to a low recommended level is associated with an increase in the prevalence of thyroid autoantibodies in the population” Clin Endocrinol 75:120-126 (2011) ... 11.04008.x

Pedersen IB, Laurberg P, Knudsen N, Jørgensen T, Perrild H, Ovesen L, Rasmussen LB - "An increased incidence of overt hypothyroidism after iodine fortification of salt in Denmark: a prospective population study" J Clin Endocrinol Metab 92(8):3122-7 (2007) doi: 10.1210/jc.2007-0732

Perez-lobato R, Ramos R, Arrebola JP, Calvente I, Ocon-Hernandez O, Dávila-Arias C, et al. - "Thyroid status and its association with cognitive functioning in healthy boys at 10 years of age" Eur J Endocrinol 172(2):129–39 (2014). INMA-Granada ... 29/6660916
"Children with TSH levels in the top tertile had worse verbal comprehension and immediate and long-term recall."

Perlasa LA, Ulanday JR, Marcos JM, Seraficob ME, Desnacido JA, Alibayan MV, Duante CA, Capanzana MV - "Iodine Deficiency Disorder Among Filipino School Children, Pregnant and Lactating Women and the Elderly 20 Years After the Act for Salt Iodization Nationwide Law" J Endocrinol Metab 7(3):86-93 (2017)
"UIE levels corresponding to excessive intakes have steadily increased and should be given equal attention as this may cause adverse health consequences such as iodine-induced hyperthyroidism and autoimmune thyroid diseases."

Rasmussen LB, Ovesen L, Christiansen E - "Day-to-day and within-day variation in urinary iodine excretion" Eur J Clin Nutr 53:401–407 (1999)

Rasmussen LB, Kirkegaard-Klitbo DM, Laurberg P, Jørgensen T, Ovesen L, Perrild H - "Iodine excretion in school children in Copenhagen" Dan Med J. 63(5):A5223 (2016) ... copenhagen
"The median UIC was within the recommended level; 145 (range: 116-201) µg/l for boys and 128 (range: 87-184) µg/l for girls, and was lower in fifth grade students than in first grade students. Estimated 24-h iodine excretion was higher in boys than in girls, but did not differ according to grade...UIC was significantly higher in children than in adults and in pregnant women from the same geographical area, but iodine excretion expressed as estimated 24-h iodine excretion was significantly lower in children than in adults."

Rebagliato M, Murcia M, Alvarez-Pedrerol M, Espada M, Fernández-Somoano A, Lertxundi N, Navarrete-Muñoz E-M, Forns J, Aranbarri A, Llop S, Julvez J, Tardón A, Ballester F - "Iodine supplementation during pregnancy and infant neuropsychological development: INMA Mother and Child Cohort Study" Am J Epidemiol 177(9):944–953 (2013) INMA

Rebagliato M, Murcia M, Espada M, Alvarez-Pedrerol M, Bolúmar F, Vioque J, Basterrechea M, Blarduni E, Ramón R, Guxens M, Foradada CM, Ballester F, Ibarluzea J, Sunyer J - "Iodine intake and maternal thyroid function during pregnancy" Epidemiology 21(1):62-9 (2010) doi: 10.1097/EDE.0b013e3181c1592b INMA ... ng.11.aspx
"There was an increased risk of TSH above 3 μU/mL in women who consumed 200 μg or more of iodine supplements daily compared with those who consumed less than 100 μg/day..."

Riis KR, Bonnema SJ, Dreyer AF, Jensen TK, Glintborg D, Bilenberg N, Bleses D, Trecca F, Andersen M - "The association between maternal thyroid function and language acquisition in offspring aged 12 to 37 months: an Odense Child Cohort study" Endocrine Abstracts (2023) 92 OP04-04 | DOI: 10.1530/endoabs.92.OP-04-04 ODENSE - OCC ... 2op-04-04/
"The probability of producing words within the MB-CDI at the age of 12 to 37 months correlated negatively with maternal FT4 in both girls and boys (P < 0.001). Likewise, language acquisition was better in both girls and boys when maternal FT4 was below the 20th percentile compared to children exposed to a maternal FT4 above the 80th percentile (P < 0.001, P = 0.002, respectively)...Language acquisition at age 12-37 months for both girls and boys was inversely correlated with TPOAb levels, as TPOAb >11 kIU/L decreased the probability of producing words compared to those with maternal TPOAb levels <11 kIU/L (P < 0.001)...Conclusion: Language acquisition in offspring at age 12-37 months correlated inversely with maternal FT4 and serological markers of thyroid autoimmunity in early pregnancy. Thus, thyroid autoimmunity per se may have a negative impact on fetal neural development. However, the finding that maternal thyroid function in the lower-normal range may be favorable for language acquisition contrasts with the current perception."

Rosique C, Lebsir D, Lestaevel P, Benatia S, Guigon P, Caire-Maurisier F, Benderitter M, Bennouna D, Souidi M, Martin JC - "Assessment of the effects of repeated doses of potassium iodide intake during pregnancy on male and female rat offspring using metabolomics and lipidomics" J Toxicol Environ Health A 82(10):603-615 (2019) ... 19.1625474
(Sustained supplementation with iodine caused a high drop in TSH in male rats only.)

Salarkia N, Mirmiran P, Azizi F - "Timing of the Effect of Iodine Supplementation on Intelligence Quotients of Schoolchildren" Int J Endocrinol Metab 2:95-102 (2004)
"It is concluded that children whose mothers received iodide supplementation before conception had normal IQs of significantly higher values than those whose mothers received iodine during pregnancy and the children who received iodine after birth."

Sang Z, Wei W, Zhao N, Zhang G, Chen W, Liu H, Shen J, Liu J, Yan Y, Zhang W - "Thyroid dysfunction during late gestation is associated with excessive iodine intake in pregnant women" J Clin Endocrinol Metab 97(8):E1363–E1369 (2012)
"Living with high water iodine content and having urinary iodine concentration higher than 250 μg/liter are associated risk factors for subclinical hypothyroidism in pregnant women (OR(1) = 41.822, OR(2) = 6.202; P < 0.05, where OR(1) is the odds ratio for living with high water iodine content and hypothyroidism and OR(2) is the odds ratio for urinary iodine concentration >250 μg/liter and hypothyroidism).”

Sang Z, Wei W, Zhao N, Zhang G, Chen W, Liu H, Shen J, Liu J, Yan Y, Zhang W - "Thyroid dysfunction during late gestation is associated with excessive iodine intake in pregnant women" J Clin Endocrinol Metab 97(8):E1363–E1369 (2012)

Schiller T, Agmon A, Ostrovsky V, Shefer G, Knobler H, Zornitzki T - “Moderate Iodine Deficiency Is Common in Pregnancy but Does Not Alter Maternal and Neonatal Thyroid Function Tests” Front Endocrinol (Lausanne) 11:523319 (2020). doi: 10.3389/fendo.2020.523319 (2020)

Schmidt M, Voell M, Rahlff I, Dietlein M, Kobe C, Faust M, Schicha H - "Long-term follow-up of antithyroid peroxidase antibodies in patients with chronic autoimmune thyroiditis (Hashimoto's thyroiditis) treated with levothyroxine" Thyroid 18(7):755-60 (2008) doi: 10.1089/thy.2008.0008
"Serum TPO-Ab levels decline in most patients with Hashimoto's thyroiditis who are taking levothyroxine."

Schmitz EM, Langelaan ML, de Groot MJ, Ermens TA, Joosen AM - "Trimester-specific reference intervals for cystatin C and neutrophil gelatinase-associated lipocalin during pregnancy" Ann Clin Biochem 59(3):199-204 (2022)

Sengupta P - "A Scientific Review of Age Determination for a Laboratory Rat: How Old is it in Comparison with Human Age?" Biomedicine International
2: 81-89 (2011) or Sengupta P - "The Laboratory Rat: Relating Its Age With Human's" Int J Prev Med 4(6):624-30 (2013)

Serrano-Nascimento C, Salgueiro RB, Pantaleão T, Corrêa da Costa VM, Nunes MT - "Maternal Exposure to Iodine Excess Throughout Pregnancy and Lactation Induces Hypothyroidism in Adult Male Rat Offspring" Sci Rep 7(1):15591 (2017)
"In conclusion, our results indicate that rat dams' exposure to IE during pregnancy and lactation induces primary hypothyroidism and triggers several epigenetic changes in the thyroid gland of their male offspring in adulthood."

Shan Z, Chen L, Lian X, Liu C, Shi B, Shi L, Tong N, Wang S, Weng J, Zhao J, Teng X, Yu X, Lai Y, Wang W, Li C, Mao J, Li Y, Fan C, Teng W - "Iodine Status and Prevalence of Thyroid Disorders After Introduction of Mandatory Universal Salt Iodization for 16 Years in China: A Cross-Sectional Study in 10 Cities" Thyroid 26(8):1125-30 (2016) doi: 10.1089/thy.2015.0613
"Compared with a five-year prospective study conducted in 1999, the prevalence of goiter significantly decreased (2.9% vs. 5.02%, p = 0.001), but there was a significant increase in thyroid nodules (12.8% vs. 2.78%, p = 0.001). The prevalence of subclinical hypothyroidism (16.7% vs. 3.22%), positive TPOAb (11.5% vs. 9.81%), and positive TgAb (12.6% vs. 9.09%) significantly increased..."

Shan Z, Teng W, Li Y, et al. - "Comparative epidemiological study on the prevalence of iodine-induced hypothyroidism" Chin J Endocrinol Metab 7:71–4 (2001) DOI: 10.3760/j.issn:1000-6699.2001.02.003
"The main cause of overt hypothyroidism was autoimmune thyroiditis; one-third of the cases with subclinical hypothyroidism showed positive thyroid autoantibodies...Higher prevalence of overt and subclinical hypothyroidism was found in the rural communities with higher iodine supply in a cross sectional epidemiologic study, suggesting a possible role of increasing or excessive iodine intake in hypothyroidism."

Shi X, Han C, Li C, Mao J, Wang W, Xie X, Li C, Xu B, Meng T, Du J, Zhang S, Gao Z, Zhang X, Fan C, Shan Z, Teng W - "Optimal and safe upper limits of iodine intake for early pregnancy in iodine-sufficient regions: a cross-sectional study of 7190 pregnant women in China" J Clin Endocrinol Metab 100(4):1630–1638 (2015) ... 30/2815136
"Multivariate logistic regression indicated that more-than-adequate iodine intake (UIC 250–499 μg/L) and excessive iodine intake (UIC ≥ 500 μg/L) were associated with a 1.72-fold and a 2.17-fold increased risk of subclinical hypothyroidism, respectively."

Shi C, Teng X, Sun W, Wei J, Shan Z, Guan H, Gao Y, Wang W, Chen W, Tong Y - "Multifactor analysis of relationship between the biological exposure to iodine and hypothyroidism" Chinese Medical Journal 14:1171-1174 (2004) (PFPC Library)
"More than adequate iodine and excessive iodine were independent risk factors of subclinical hypothyroidism (OR =3.172 and 6.391, P <0.05) and overt hypothyroidism (OR =3 696 and 9.213, P <0.05). When interactions of iodine exposure and thyroid peroxidase antibody (TPOAb) or thyroglobulin antibody (TgAb ) were included, more than adequate iodine was still a risk factor of subclinical hypothyroidism (OR =2.788, P <0.01), but had no such effect on overt hypothyroidism. Interaction of more than adequate iodine and positive TgAb significantly affected subclinical hypothyroidism and overt hypothyroidism (OR =2.656 and 3.347, P <0.05). More than adequate and excessive iodine exposure are independent risk factors of hypothyroidism. The risk of hypothyroidism grows and thyroid dysfunction becomes more serious with the increasing of the biological exposure to iodine."

Shrestha U, Gautam N, Agrawal KK, Jha AC, Jayan A - "Iodine Status among Subclinical and Overt Hypothyroid Patients by Urinary Iodine Assay: A Case-Control Study" Indian J Endocrinol Metab 21(5):719-723 (2017) doi: 10.4103/ijem.IJEM_413_16 ... rt.16.aspx
"A significantly higher median UIC was observed among cases of subclinical hypothyroidism (224.90 μg/l) and overt hypothyroidism (281.0 μg/l) as compared to the controls (189.90 μg/l) (P = 0.0001, P = 0.001).”

Silva de Morais N, Ayres Saraiva D, Corcino C, Berbara T, Schtscherbyna A, Moreira K, Vaisman M, Alexander EK, Teixeira P - "Consequences of Iodine Deficiency and Excess in Pregnancy and Neonatal Outcomes: A Prospective Cohort Study in Rio de Janeiro, Brazil" Thyroid 30(12):1792-1801 (2000) doi: 10.1089/thy.2019.0462
"In a population whose median iodine intake is sufficient, extensive individual variation occurs. Such abnormalities are associated with increased GDM [Gestational Diabetes] and HDP [hypertensive disorders of pregnancy] when UIC is ≥250 μg/L, and lower infant birth length when UIC is <150 μg/L."

Sokoloff K, Fraser W, Arbuckle TE, Fisher M, Gaudreau E, LeBlanc A, Morisset AS, Bouchard MF - “Determinants of urinary concentrations of dialkyl phosphates among pregnant women in Canada - Results from the MIREC study” Environ Int 94:133-140 (2016) doi: 10.1016/j.envint.2016.05.015 MIREC ... 201630188X

Soldin OP - "Thyroid function testing in pregnancy and thyroid disease: trimester-specific reference intervals" Ther Drug Monit 28(1):8-11 (2006)
doi: 10.1097/01.ftd.0000194498.32398.7b

Soldin OP- " Controversies in urinary iodine determinations" Clin Biochem 35(8):575-9 (2002) doi: 10.1016/s0009-9120(02)00406-x
"It is normal for the GFR to be as much as 50% higher during pregnancy...A higher GFR during pregnancy results in decreased circulating creatinine and a possible trend toward lower urinary creatinine concentrations...a higher requirement for iodine during pregnancy might lead to a lower UI/Cr ratio. In mild ID the correlation between UI concentrations and UI/Cr ratio was lower for pregnant women than for nonpregnant women."

Song J, Zou SR, Guo CY, Zang JJ, Zhu ZN, Mi M, Huang CH, Yu HT, Lu X, Ruan Y, Wu F - "Prevalence of Thyroid Nodules and Its Relationship with Iodine Status in Shanghai: a Population-based Study" Biomed Environ Sci 29(6):398-407 (2016) doi: 10.3967/bes2016.052 ... es2016.052

Statistics Canada - Canadian Health Measures Survey (CHMS) 2009-2011 ... y&Id=62444 Stilwell G, Reynolds PJ, Parameswaran V, Blizzard L, Greenaway TM, Burgess JR - "The influence of gestational stage on urinary iodine excretion in pregnancy" J Clin Endocrinol Metab 93(5):1737-42 (2008) doi: 10.1210/jc.2007-1715

Stinca S, Andersson M, Weibel S, Herter-Aeberli I, Fingerhut R, Gowachirapant S, Hess SY, Jaiswal N, Jukic T, Kusic Z, Mabapa NS, Nepal AK, San Luis TO, Zhen JQ, Zimmermann MB - “Dried Blood Spot Thyroglobulin as a Biomarker of Iodine Status in Pregnant Women” J Clin Endocrinol Metab 102(1):23-32 (2017). doi: 10.1210/jc.2016-2829

Sun Ning, Chen Gan, Xie Zhiqiang, Wang Yanli, Zhang Li, Hao Zongyu, Zheng Heming - "Study on the correlation of iodine and fluoride excretion in drinking water with normal fluoride and iodine" Contemporary Medicine 18 (2013) ... 318110.htm
Researchers withdrew iodized salt for two months, tested before and after in areas with "normal" fluoride in water supply (0.42 ~ 0.95 ppm, average of 0.73 ppm). When iodine intake was reduced while fluoride intake remained unchanged: urine iodine excretion decreased, urinary fluoride excretion increased.

Sun R, Qian TT, Liu LC, Zhao MC, Che WJ, Zhang LL, Li WD, Whang JH, Chen ZH, Zhang BY, Liu P - "Effect of Iodine Supplementation on Iodine Nutrition and Thyroid Function in Pregnant Women: A Cross-Sectional Study" China CDC Study, Biomedicine and Environmental Science: English Edition (7):641-647 (2022) ... 7107886714
"In addition, pregnant women with MUIC in the 150–249μg/L range showed higher rates of TPOAb-positive (13.78%) disease and sub-hypothyroidism (5.38%) compared to those with MUIC in the 100–149μg/L range; however, goiter showed the opposite trend. Our results indicate that iodine supplementation needs vary from person to person." (See also Wu, 2017)

Sun J, Teng D, Li C, Peng S, Mao J, Wang W, Xie X, Fan C, Li C, Meng T, Zhang S, Du J, Gao Z, Shan Z, Teng W - "Association between iodine intake and thyroid autoantibodies: a cross-sectional study of 7073 early pregnant women in an iodine-adequate region" J Endocrinol Invest 43(1):43-51 (2020). doi: 10.1007/s40618-019-01070-1 ... 19-01070-1
NOTE: U-shape - UIC

Tan L, Sang Z, Shen J, Liu H, Chen W, Zhao N, Wei W, Zhang G, Zhang W - "Prevalence of thyroid dysfunction with adequate and excessive iodine intake in Hebei Province, People's Republic of China" Public Health Nutr 18(9):1692-7 (2015) doi: 10.1017/S1368980014002237 ... E574A4C6D8

Teng W, Shan Z, Teng X, Guan H, Li Y, Teng D, Jin Y, Yu X, Fan C, Chong W, Yang F, Dai H, Yu Y, Li J, Chen Y, Zhao D, Shi X, Hu F, Mao J, Gu X, Yang R, Tong Y, Wang W, Gao T, Li C - "Effect of iodine intake on thyroid diseases in China" N Engl J Med 354(26):2783-93 (2006) doi: 10.1056/NEJMoa054022.
"We observed an increase in the prevalence of overt hypothyroidism, subclinical hypothyroidism, and autoimmune thyroiditis with increasing iodine intake in China in cohorts from three regions with different levels of iodine intake: mildly deficient (median urinary iodine excretion, 84 μg per liter), more than adequate (median, 243 μg per liter), and excessive (median, 651 μg per liter)...Among subjects with euthyroidism and antithyroid antibodies at baseline, the five-year incidence of elevated serum thyrotropin levels was greater among those with more than adequate or excessive iodine intake than among those with mildly deficient iodine intake.

Teti C, Panciroli M, Nazzari E, Pesce G, Mariotti S, Olivieri A, Bagnasco M - "Iodoprophylaxis and thyroid autoimmunity: an update" Immunol Res 69(2):129-138 (2021) doi: 10.1007/s12026-021-09192-6
"In conclusion, available data from long-term population surveys show that a higher than adequate population iodine intake due to a poorly controlled program of iodine prophylaxis could induce thyroid dysfunction, including thyroid autoimmunity mostly represented by euthyroid or subclinical hypothyroid autoimmune thyroiditis."

Thomas DB, Basu N, Martinez-Mier EA, Sánchez BN, Zhang Z, Liu Y, Parajuli RP, Peterson K, Mercado-Garcia A, Bashash M, Hernández-Avila M, Hu H, Téllez-Rojo MM - "Urinary and plasma fluoride levels in pregnant women from Mexico City" Environ Res 150:489-495 (2016) ELEMENT ... 5116302808
"Upon enrollment women were not screened for renal problems that could potentially affect the urinary fluoride levels. The early morning 2nd voided urine samples and plasma samples we measured were not taken with the requirement that each subject be in the fasting state, which may have introduced variability. However, the early morning 2nd void nature of the urine specimens would have reduced time-of-day variations driven by diurnal metabolic changes, and the adjustment by creatinine corrected for urinary dilution. Nonetheless, future studies should either provide 24-hour measures or measure samples that have been collected after fasting."

Till C, Green R, Grundy JG, Hornung R, Neufeld R, Martinez-Mier EA, Ayotte P, Muckle G, Lanphear B - "Community Water Fluoridation and Urinary Fluoride Concentrations in a National Sample of Pregnant Women in Canada" Environ Health Perspect 126(10):107001 (2018) doi: 10.1289/EHP3546 MIREC
"There are several limitations of this study. First, overnight fasting or 24-h urine samples are considered to be the optimal dosimeter for measuring chronic fluoride exposure (WHO 2014). In contrast, the present study measured the concentration of fluoride in a spot urine sample that did not control for recent fluoride ingestion. Urinary fluoride concentration does not measure total exposure (intake) nor did we estimate the 24-h daily urinary fluoride excretion level, which would require multiplying our fluoride:creatinine ratio by a standard creatinine value (not established to our knowledge for each trimester of pregnancy)...We noted that 11% of women had different postal codes between trimesters, although we presume some of these women moved within the same WTP zone."

Till C, Green R, Flora D, Hornung R, Martinez-Mier EA, Blazer M, Farmus L, Ayotte P, Muckle G, Lanphear B - "Fluoride exposure from infant formula and child IQ in a Canadian birth cohort" Environ Int 134:105315 (2020) doi: 10.1016/j.envint.2019.105315 MIREC ... 19)32614-5
[NOTE: No efforts undertaken to investigate iodine content in formula or the use of iodine supplements during lactation. By law, infant formula in Canada has to contain iodine, usually at 5 ug per 100 calories. If one liter of formula is approx 800 calories, then this would mean 40 ug from this source alone, roughly close to the 50 ug/day advised by the WHO. The percentages of mothers that used a multivitamin-mineral (MVM) supplement containing iodine were 79% and 59% at 1 and 6 months of lactation, respectively." (Bertinato et al., 2022)]

Wang B, He W, Li Q, Jia X, Yao Q, Song R, Qin Q, Zhang JA - "U-shaped relationship between iodine status and thyroid autoimmunity risk in adults" Eur J Endocrinol 181(3):255-266 (2019) doi: 10.1530/EJE-19-0212 ... 55/6654156
"The study suggests an U-shaped relationship between iodine intake and TAI in adults, and both iodine deficiency and iodine excess are risk factors of TAI in adults."

Wang X, Jia T, Liu D - "Iodine nutrition and thyroid autoantibodies in pregnancy and their relation to thyroid function" Chinese Journal of Endocrinology and Metabolism 5:408-410 (2014)
"The levels of serum thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody were markedly related to serum TSH ( P<0.01 ), so was the level of serum TPOAb related to serum FT4 (P < 0.05)...Therefore, we advocate the screening of urine iodine and thyroid autoantibodies before or during the first trimester of pregnancy, aiming to correct iodine deficiency, avoiding supplementing too much iodine, improve the outcome of perinatal stage, and reduce all the negative effects on the offspring."

Wang W, Zhang Y, Tan L, San G, Zhang W - "Study on Effects of Iodine Excess on Brain and Serum Concentrations of Monoamine Neurotransmitters in Rats" - Acta Nutrimenta Sinica 39(2)200-202 (2017)
Notice the inverse U-shaped (V) effects of iodine on dopamine [C] in brain of rats.

Wang T, Liu Y, Kong Q, Cao X, Liu Y, Xia S, Zheng T, Yu L - "Effect of Moderate-to-Severe Iodine Deficiency in Early Pregnancy on Subclinical Hypothyroidism: A Longitudinal Study in an Iodine-Sufficient Region in China" Front Nutr 9:839651 (2022) doi: 10.3389/fnut.2022.839651 ... 39651/full

Wang PW, Wang ST, Liu RT, Chien WY, Tung SC, Lu YC, Chen HY, Lee CH - "Levothyroxine suppression of thyroglobulin in patients with differentiated thyroid carcinoma" J Clin Endocrinol Metab 84(12):4549-53 (1999) doi: 10.1210/jcem.84.12.6190.

Wang Y, Cui Y, Chen C, Duan Y, Wu Y, Li W, Zhang D, Li F, Hou C - "Stopping the supply of iodized salt alone is not enough to make iodine nutrition suitable for children in higher water iodine areas: A cross-sectional study in northern China" Ecotoxicol Environ Saf 188:109930 (2020) doi: 10.1016/j.ecoenv.2019.109930 ... 1319312618
"Binary logistic regression analysis indicated that the risk of thyroid abnormalities was significantly increased in the UIC 200–299 μg/L group (OR: 4.534; 95% CI: 1.565, 13.135; bootstrapped 95% CI: 1.689, 21.206, P = 0.004) and in the UIC ≥ 300 μg/L group (OR: 6.962; 95% CI: 2.490, 19.460; bootstrapped 95% CI: 2.838, 32.570, P = 0.001) compared to the 100–199 μg/L group."

Wang R - "Effects of high fluoride and high iodine combination on thyroid damage and mental development" Master's Thesis, Tianjin University (2010) ... VOaGo6_xMt

Wang K, Zhang J, Li F, Zhang W, Wang H, Ding L, Liu Y, Lin L, Zhang S, Zhu M - "Urinary iodine in early pregnancy is associated with subclinical hypothyroidism in Tianjin, China: an observational study" BMC Endocr Disord 17(1):10 (2017) doi: 10.1186/s12902-017-0162-x
"UIC ≥ 250 μg/L was associated with increased risk of SH. Serological negative autoimmune thyroiditis and UIC ≥ 250 μg/L may play a role in pathogenesis of SH cases with negative results for autoantibodies."

Wang YG, Yan S, Zhao S, Wang F, Yu X - "Correlation of Hashimoto′s thyroiditis with urine iodine level among the coastal districts in Shandong Province" Chinese Journal of Endocrinology and Metabolism 4:337-338 (2004)
"Urinary iodine level showed positive correlation with thyroglobulin antibody and thyroid peroxidase antibody, suggesting the urinary iodine level is better to be controlled under 300 μg/L in the residents along the coast."

Wasserman EE, Pillion JP, Duggan A, Nelson K, Rohde C, Seaberg EC, Talor MV, Yolken RH, Rose NR - "Childhood IQ, hearing loss, and maternal thyroid autoimmunity in the Baltimore Collaborative Perinatal Project" Pediatr Res 72(5):525-30 (2012) doi: 10.1038/pr.2012.117
Evidence obtained from the Baltimore Collaborative Perinatal Project showed that maternal TPOAb positivity was associated with lower IQ in children at 4 years of age - same age as the MIREC children.

Webster GM, Venners SA, Mattman A, Martin JW - "Associations between perfluoroalkyl acids (PFASs) and maternal thyroid hormones in early pregnancy: a population-based cohort study" Environ Res 133:338-47 (2014) doi: 10.1016/j.envres.2014.06.012 ... 5114002084

World Health Organization. Worldwide Iodine Status. In WHO Global Database on Iodine Deficiency; Department of Nutrition for Health and Development World Health Organization: Geneva, Switzerland (2004) ... 592001.pdf

WHO/UNICEF/ICCIDD - "Assessment of iodine deficiency disorders and monitoring their elimination: a guide for programme managers" 3rd ed., Geneva: World Health Organization (2007) ... 27_eng.pdf

WHO Secretariat; Andersson M, de Benoist B, Delange F, Zupan J - “Prevention and control of iodine deficiency in pregnant and lactating women and in children less than 2-years-old: conclusions and recommendations of the Technical Consultation” Public Health Nutr 10(12A):1606-11 (2007) doi: 10.1017/S1368980007361004 ... 23896F2120

Winder M, Kosztyła Z, Boral A, Kocełak P, Chudek J - "The Impact of Iodine Concentration Disorders on Health and Cancer" Nutrients 14(11):2209 (2022) doi: 10.3390/nu14112209

Wu N, Zhao ZL, et al. - "Effects of low doses of fluoride on thyroid function of young rats" Chinese Journal of Control of Endemic Diseases 8(4):244 (1993)

Wu M - "Study on appropriate threshold value of urinary iodine during pregnancy" Chinese Center for Disease Control and Prevention (2017)
Wu found that the appropriate MUIC in pregnant women was far below that recommended by the World Health Organization - subjects with UIC in of 100-150ug/L had normal thyroid function. (See also most recent Chinese CDC study - Sun et al., 2022)

Xu K, An N, Huang H, Duan L, Ma J, Ding J, He T, Zhu J, Li Z, Cheng X, Zhou G, Ba Y - "Fluoride exposure and intelligence in school-age children: evidence from different windows of exposure susceptibility" BMC Public Health 20(1):1657 (2020) doi: 10.1186/s12889-020-09765-4.
NOTE: This article has been retracted. None of the authors agree with the retraction. Retraction in: BMC Public Health. 2022 Nov 8;22(1):2044.

Xu T, Ren Z, Li S, Tan L, Zhang W - "The relationship of different levels of high iodine and goiter in school children: a meta-analysis" Nutr Metab (Lond) 18(1):46 (2021) doi: 10.1186/s12986-021-00563-2
"When the UIC ≥ 300 μg/L or the WIC ≥ 100 μg/L, the risk of goiter will increase. The higher the UIC, the greater the risk of goiter development. In order to improve the public thyroid health, we should adhere to the monitoring of urinary iodine and water iodine, and keep them at an appropriate level."

Xu Y, Chen H, Ren M, Gao Y, Sun K, Wu H, Ding R, Wang J, Li Z, Liu D, Wang Z, Yan L - "Thyroid autoimmunity and adverse pregnancy outcomes: A multiple center retrospective study" Front Endocrinol (Lausanne) 14:1081851 (2023) doi: 10.3389/fendo.2023.1081851 ... 81851/full
"TSH concentrations was higher in TAI women in baseline and remain higher before the third trimester. Positive thyroid autoantibodies were independently associated with higher risk of pregnancy-induced hypertension, gestational diabetes mellitus, and neonatal admission to NICU...increasing TPOAb concentration was correlated with higher probability of pregnancy-induced hypertension, and increasing TGAb concentration was positively correlated with pregnancy-induced hypertension, small for gestational age and NICU admission. Both TPOAb and TGAb concentration were negatively associated with neonatal birthweight." [see also: Nazarpour et al., 2023]

Yan R, Xu R, Zhou Y, Li Y, Pang Y, Liu J, Hu XH, Yang FG, Wen S, Zhang LP, Liu MQ - "Effects of iodine and fluoride content in drinking water on prevalence of adults thyroid nodules in Cangzhou, Hebei" Journal of Environmental and Occupational Medicine 36(5): 470-47 (2019) ... 2019.18828
"Both high iodine and low iodine can induce thyroid nodules. In water source areas with high iodine content, both high iodine and high fluorine are the factors inducing thyroid nodules. The prevalence of thyroid nodules in low iodine and high fluorine area is significantly higher than that of low iodine area."

Yan DE, Hu L, Shen YF, Lai XY, Zhang MY, Zhou M, Chen C, Liu MM, Wu LT, Liu LQ, Fan QW, Min WL, Wan SC, Zou F, Li J, Cai X, Lei SH, Xiong Y, Yang Y, Yu R, Gao WW, Zhang Y, Chen T - "Iodine status and its association with prevalence of thyroid diseases in adults from Jiangxi Province, China" Endocrine 2023 Jun 12. doi: 10.1007/s12020-023-03413-8. Epub ahead of print ... 23-03413-8
"Both iodine deficiency and excessive iodine were risk factors for TAI."

Yang L, Li M, Liu X, Wu M, Zhang J, Zhao L, Ding G, Yang X - "Evaluation of Iodine Nutritional Status Among Pregnant Women in China" Thyroid 30(3):443-450 (2020). doi: 10.1089/thy.2019.0001
"Pregnant women with UIC >250 μg/L had higher TSH levels than those with UIC 120-149 and 150-249 μg/L ...Compared with pregnant women who had UIC <250 μg/L, the prevalence of subclinical hypothyroidism was significantly increased in those with UIC >250 μg/L."
NOTE: In this study of the 2015 China National Nutrition and Health Survey (CNNHS), UIC was analyzed in a total of 6173 urinary samples collected from pregnant women residing in 31 provinces of China.

Yang Q, Zhou J, Xue B, Jiang Y, Zhang L - "Study on the correlation between urinary iodine level and thyroid function" Systems Medicine 2:07-110 (2023)
"In the comparison of the three groups, the urinary iodine level in the hypothyroidism group [265.2 (165.56, 284.56) μg/L] was significantly higher, and the difference was statistically significant (F=3.825, P=0.022). The double-positive rate of TGAb and TPOAb in the hypothyroidism/subclinical hypothyroidism group (14.3%) was higher than that in the normal thyroid function group, and the difference was statistically significant (P<0.05)...There was a negative correlation between urinary iodine level and TPOAb (r=-0.212, P=0.001). Iodine intake status may be associated with autoimmune hypothyroidism."

Yang XF, Hou XH, Jian XW, Guo HL, Ying CJ, Chen XY, Sun XF - "Effect of Selenium Supplementation on Activity and mRNA Expression of Type 1 Deiodinase in Mice With Excessive Iodine Intake" Biomed Environ Sci 19(4):302-8 (2006) PMID: 17044649.
"Excessive iodine intake significantly decreased the selenium concentration in urine and liver, and the activity of glutathione peroxidase (GSH-Px) in liver. Meanwhile, serum total T4 (TT4) increased while serum total T3 (TT3) decreased. Hepatic D1 enzyme activity and mRNA expression were reduced by 33% and 86%, respectively. Renal D1 enzyme activity and mRNA were reduced by 30% and 55%, respectively. Selenium supplementation obviously increased selenium concentration, activity of GSH-Px and D1 as well as mRNA expression of D1...Conclusion: Relative selenium deficiency caused by excessive iodine plays an essential role in the mechanism of iodine-induced abnormalities. An appropriate dose of selenium supplementation exercises a beneficial intervention."

Yu X, Chen J, Li Y, Liu H, Hou C, Zeng Q, Cui Y, Zhao L, Li P, Zhou Z, Pang S, Tang S, Tian K, Zhao Q, Dong L, Xu C, Zhang X, Zhang S, Liu L, Wang A - "Threshold effects of moderately excessive fluoride exposure on children's health: A potential association between dental fluorosis and loss of excellent intelligence" Environ Int 118:116-124 (2018) doi: 10.1016/j.envint.2018.05.042 ... 1201830480

Yu X, Xia L, Zhang S, Zhou G, Li Y, Liu H, Hou C, Zhao Q, Dong L, Cui Y, Zeng Q, Wang A, Liu L - "Fluoride exposure and children's intelligence: Gene-environment interaction based on SNP-set, gene and pathway analysis, using a case-control design based on a cross-sectional study" Environ Int 155:106681 (2021). doi: 10.1016/j.envint.2021.106681 ... 2021003068

Zhang X, Yuan N, Sun J, Zhao X, Du J, Nan M, Zhang Q, Ji L - "Association Between Iodine Nutritional Status and Adverse Pregnancy Outcomes in Beijing, China: a Single-Center Cohort Study" Biol Trace Elem Res 200(6):2620-2628 (2022). doi: 10.1007/s12011-021-02887-9
"The relationship between UI and the concentrations of TPOAb and TGAb follows a nearly U-shaped curve. Thus, physicians should critically consider the iodine nutritional status of pregnant women during the first trimester."

Zhao L, Teng D, Shi X, Li Y, Ba J, Chen B, Du J, He L, Lai X, Li Y, Chi H, Liao E, Liu C, Liu L, Qin G, Qin Y, Quan H, Shi B, Sun H, Tang X, Tong N, Wang G, Zhang JA, Wang Y, Xue Y, Yan L, Yang J, Yang L, Yao Y, Ye Z, Zhang Q, Zhang L, Zhu J, Zhu M, Shan Z, Teng W - "The Effect of Increased Iodine Intake on Serum Thyrotropin: A Cross-Sectional, Chinese Nationwide Study" Thyroid 30(12):1810-1819 (2020) doi: 10.1089/thy.2019.0842
"Serum TSH concentration significantly increased with increase in iodine intake. Thus, iodine intake must be considered in establishing TSH reference intervals."

Zhou BQ, Wang WL, Zhuang JF - "Research on correlation of urinary iodine and urinary fluoride" Modern Preventive Medicine 35(17): 3411-3412 (2008) ... 817065.htm ... d=28073250
Subjects: Patients with simple goiter and cretinism who took iodine preparations. Urinary iodine was higher than that of local normal people who did not take iodine preparations, and urine fluoride was lower than that of normal people who did not take iodine preparations. "So it indicates that urinary iodine and urinary fluoride negatively correlate to each other."
Supplements__Iodine: (126.5±25.8 μg/L)___Fluoride: (0.37±0.11 mg/L)
Normal_______Iodine: (87.1±27.1 μg/L)____Fluoride: (0.57±0.13)mg/L

Zhou SJ, Condo D, Ryan P, Skeaff SA, Howell S, Anderson PJ, McPhee AJ, Makrides M - "Association Between Maternal Iodine Intake in Pregnancy and Childhood Neurodevelopment at Age 18 Months" Am J Epidemiol 188(2):332-338 (2019) doi: 10.1093/aje/kwy225
"The association between high maternal iodine intake (quartile 4) and poorer Bayley-III outcome in children, as well as our estimate of the effect, are compatible with the findings from a Spanish cohort study (INMA (23, 24)) in an iodine-sufficient area, which reported a 5.2-points-lower score in the Bayley-II (23) and a 1.7- (24) to 1.8-fold (23) increase in the odds of developmental delay in children whose mothers took iodine supplements of ≥150 μg/ day during pregnancy compared with those who took iodine supplements below 100 μg/day or no supplements. The background mean dietary iodine intake of the women in our study (150 μg/ day) (25) is similar to that of women from the Sabadell region in the INMA study (146 μg/day) (24). While these associations do not prove a causal relationship, the inhibitory effect of excess iodine on thyroid function is well recognized (26). The fetal thyroid is sensitive to the inhibitory effect of excess iodine, and excess iodine intake in pregnancy has also been shown to induce hypothyroidism in neonates (27–29). Findings from our study and the Spanish studies (23, 24) highlight the need to closely monitor and assess the safety of current recommendations in iodine sufficient populations like the United States and Australia after iodine fortification (25, 30, 31), because it is possible that some women might consume too much iodine."

Zimmermann MB - "Iodine deficiency in pregnancy and the effects of maternal iodine supplementation on the offspring: a review" Am J Clin Nutr 89(2):668S-72S (2009) doi: 10.3945/ajcn.2008.26811C ... 6523239829

Zimmermann MB, Andersson M - “Assessment of iodine nutrition in populations: past, present, and future” Nutr Rev 70:553–70 (2012) ... 53/1879576

Zimmermann MB, Aeberli I, Andersson M, Assey V, Yorg JA, Jooste P, Jukić T, Kartono D, Kusić Z, Pretell E, San Luis TO Jr, Untoro J, Timmer A - “Thyroglobulin is a sensitive measure of both deficient and excess iodine intakes in children and indicates no adverse effects on thyroid function in the UIC range of 100-299 μg/L: a UNICEF/ICCIDD study group report” J Clin Endocrinol Metab 98(3):1271-80 (2013) doi: 10.1210/jc.2012-3952

Zohouri FV, Swinbank CM, Maguire A, Moynihan PJ - "Is the fluoride/creatinine ratio of a spot urine sample indicative of 24-h urinary fluoride?" Community Dent Oral Epidemiol 34(2):130-8 (2006) doi: 10.1111/j.1600-0528.2006.00269.x ... 06.00269.x

Related PFPC Member Forums

Excess Iodine & IQ | Neurodevelopment

UIC > 250 ug/L

UIC in Pregnancy | Thyroid Hormones

Fluoride & Iodine



The Wistar Rat Model | Fluorosis Animal Models

The Chicken Model | Fluorosis Animal Models

Iodine Deficiency | Excess | Thyroid Disorders

Thyroid Status & eGFR

Thyroid Antibodies

Selenium, Fluoride & Iodine

Creatinine - Specific Gravity - Thyroid Function - UIC/Cr - UIC - GFR

Tianjin Notes


Press Releases published in February 2023 on the study by Hall et al.

Press Releases published in October 2023 on the study by Grandjean et al.

SDU PRESS Release on the 2023 study by Grandjean, Till, Goodman, et al.:
"Danish data support fluoride being toxic to brain development" October 10, 2023 ... elligensen
(False claim. Danish data does NOT support fluoride being toxic to brain development at the fluoride levels indicated)
  • FAN Facebook Post, October 12, 2023 (NOTE: Grandjean is an 'expert' witness on behalf of FAN in lawsuit vs EPA)

Link to FAQ (PFPC Members): viewforum.php?f=106
Post Reply