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2017 Urinary Iodine and Fluoride in Lebanese Children

Posted: Sat Jul 04, 2020 8:47 pm
by doctorJ
Ghattas H, Francis S, El Mallah C, Shatila D, Merhi K, Hlais S, Zimmermann M, Obeid O - "Lebanese children are iodine deficient and urinary sodium and fluoride excretion are weak positive predictors of urinary iodine" Eur J Nutr 56(2):749-755 (2017) ... 015-1120-x

NOTE: Since the 1930s has it been shown that iodine and fluoride levels in urine or serum have, in essence, an antagonistic relationship (Kraft 1937a, b; May, 1950; Zhou et al., 2008; Cong, 2012).

The presumption that fluoride does not interfere with iodine metabolism based on urinary iodine levels is entirely incorrect. Thyroid hormones need to be measured, as well as TSH. Urinary iodine levels from spot urine samples, even at levels below the WHO recommendation, have no significant relationship with thyroid biomarkers TSH, FT3 and FT4 in children and adolescents (Wallborn et al., 2020).

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Purpose: To assess iodine and fluoride status among Lebanese children.

Methods: A nationally representative cross-sectional study of 6- to 10-year-old schoolchildren was conducted using multistage cluster sampling. Spot urine samples were collected from 1403 children, and urinary iodine, fluoride, creatinine and sodium levels were measured. Salt samples from markets (n = 30) were tested for iodine concentration by titration.

Results: Median urinary iodine concentration was 66.0 µg/l, indicating mild deficiency, and almost 75 % of Lebanese children had a urinary iodine concentration (UIC) <100 µg/l. UIC was higher among children from private schools and in areas of higher socioeconomic status. Most salt samples were fortified at levels far below the legislated requirement, and 56 % of samples contained less than 15 ppm iodine. Fluoride-to-creatinine ratio (F/Cr) was 0.250 (0.159-0.448) mg/g. There were weak positive correlations between UIC and urinary sodium (r 2 = 0.039, P value <0.001) and UIC and urinary fluoride (r 2 = 0.009, P value <0.001).

Conclusions: Lebanese elementary school children are iodine deficient due to inadequately iodized salt. The weak correlation between UIC and urinary sodium suggests most dietary iodine does not come from iodized salt. The poor correlation between UIC and urinary fluoride suggests that fluoride intake is not affecting iodine metabolism. Efforts are needed in Lebanon to improve industry compliance with salt fortification through improved monitoring and enforcement of legislation.

Wallborn T, Vogel M, Kneuer A, Thamm M, Dittrich K, Kiess W, Kratzsch J - "Spot urine iodine levels below the WHO recommendation are not related to impaired thyroid function in healthy children and adolescents" Eur J Nutr (2020)

Zhou B, Wang W, Zhuang J - "Correlation analysis of urine iodine and urine fluoride" Mod Prev Med 17 (2008) ... 817065.htm