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Effects of addition of fluorine in diets differing in protein content on urinary fluoride excretion, clinical chemistry and thyroid hormones in calves

[N]o effect of F on thyroid hormones was noticed in the present study. This was contradictory to the findings of Wheeler & Feel (1983), who reported a significant fall in T3 and T4 levels because of adverse impact of fluorosis on the thyroid glands. It was reported that 250 mg/kg and 400 mg/kg F in diet significantly decrease serum T4 and FT4 levels and increase serum TSH, but no significant differences were observed in serum T3 and FT3 after 50 days of treatment (Zhan et al., 2006). S