"It is also evidenced that fluoride in excess may be inducing disease normally attributed to iodine deficiency." (Shashi, 2013)
Shashi A, Singla S - "Clinical and Biochemical Profile of Deiodinase Enzymes and Thyroid Function Hormones in Patients of Fluorosis" Australian Journal of Basic and Applied Sciences,7(4): 100-107 (2013)
Abstract: The thyroid involvement is very significant feature of fluorosis due to fluoride accumulation in soft tissues. The participation of long term consumption of fluoride in drinking water on thyroid hormone status and deiodinating enzymes in fluorotic patients selected randomly from various parts of fluoride endemic areas, was elucidated. Type I (D1) activity was depressed significantly (P<0.001) in all fluorotic study groups in comparison to control, while type-II (D2) activity was lowered significantly (P<0.05) only in study group A-III (8.01-12.00 mg/L) and A-IV (12.01-16.00 mg/L). Serum TSH level was significantly (P<0.001) increased in fluoride exposed groups in comparison to control group whereas the level of rT3 showed a stepwise elevation with increase in water fluoride concentration. Decreased triiodothyronin (T3), thyroxine (T4), free T3 (FT3), free T4 (FT4) levels in serum were noted in all the fluorotic study groups (P<0.01) in comparison to the control. Pearson’s bivariate correlation analysis revealed significant (P<0.05-0.001) negative relationship between serum F vs D1 (r= -0.93); serum F vs D2 (r= -0.95); serum F vs T3 (r= -0.84) and serum F vs T4 (r = -0.87). There was direct correlation between serum F and rT3 (r = 0.84, P<0.004). Partial correlation analysis exhibited positive relationship between T3 and D1 (r= 0.96) and negative relationship between rT3 and D1. The regression coefficient of activity of D1 and serum F in all fluorotic paients revealed that water F being the strong predictor of involvement in depletion of D1 activity and increased levels of serum F. The lower activity of both D1 and D2 contribute to decrease in conversion of T4 toT3 and increased conversion of T4 to rT3. The depressed activity of D1 results in reduced conversion of rT3 into T2 and thereby allowing rT3 to accumulate in the body, resulting in hypothyroidism in fluoride intoxication.
Singla S, Shashi A - "Thyroid peroxidase activity as toxicity target for fluoride in patients with thyroid dysfunction" Current Research in Microbiology and Biotechnology 1(2):53-57 (2013)
The present study aimed to assess the effects of drinking water fluoride (F) on the activity of thyroid peroxidase (TPO) enzyme involved in thyroid hormone synthesis. 840 fluorotic patients affected with thyroid hypo and
hyper function and 140 euthyroid without fluorosis representing control were randomly selected from high endemic fluoride areas of Bathinda district, Punjab, India. The findings indicate significant (P<0.001) increase in the levels of serum F, urinary F and Urinary iodine (I) in fluorotic patients affected with thyroid disease. Significant (P<0.001) inhibition was recorded in activity of TPO in fluorotic patients with thyroid hypofunction
and the activity was elevated in hyperthyroid fluorotic patients. Pearson’s bivariate correlation revealed strong positive correlation between water F and serum F (r= 0.98, P<0.01). Negative correlation existed between serum F vs TPO (r= -0.93, P<0.003), urinary I vs TPO (r = -0.95, P<0.002) and serum TSH vs TPO (r = -0.8876, P<0.001). The activity of TPO showed positive correlation with T3 (r = 0.963, P<0.01) as well as with T4 (r = 0.965, P<0.001). From the present study it may be concluded that the ingestion of drinking water with high concentration of fluoride leads to stress of the mechanism of biosynthesis of thyroid hormones, as evidenced by depletion in the activity of TPO, which may be produced by the attraction of fluoride with oxidized form of iodide and/or with the iodide site on the TPO molecule. This tends to decrease in concentration of T3, T4 and increase production of TSH in the serum.
http://crmb.aizeonpublishers.net/conten ... b53-57.pdf
Shashi A, Singla S - "Syndrome of Low Triiodothyroinine in Chronic Fluorosis" International Journal of Basic and Applied Medical Sciences 3(1):152-160 (2013)
The present study examined the thyroid function and low T3 state in a group of patients exposed to different concentration of fluoride in drinking water. 139 subjects from severe endemic fluorosis areas and 140 subjects as control group were randomly selected. The functional activity of thyroid gland was measured and the findings indicate that the level of TSH and rT3 was significantly (P<0.001) elevated and of T3 was declined in the fluorotic group. The T4 concentration showed significant (P<0.05) elevation in A-III and A-IV groups, however the elevation in A-I and A-II was not statistically significant. The level of fluoride (F) in serum and urine was significantly (P<0.001) higher in fluorotic study groups as compared to control group. Pearson’s bivariate coefficient of correlation revealed a positive relationship between water F vs. TSH (r= 0.98), water F vs. rT3 (r= 0.77) in different study groups. An inverse correlation existed between serum F vs. T3 (= -0.82) and serum F vs. T4 (r= -0.88). The study demonstrate that abnormalities in thyroid function characterized by a low level of T3, high rT3 and a slight increase of the TSH with normal to low T4 indicating low T3 syndrome in cases of chronic fluoride intoxication. It is also evidenced that fluoride in excess may be inducing disease normally attributed to iodine deficiency. The normal or optimal levels of iodine in the urine and the low level of T3 with higher level of rT3 can serve as a diagnostic sign of chronic fluoride exposure.
http://www.cibtech.org/J%20MEDICAL%20SC ... 52-160.pdf
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