We aimed to investigate the relationship between the effects excessive of fluoride on thyroid health in children and the moderating role of thyroid stimulating hormone receptor (TSHR) or protein tyrosine phosphatase nonreceptor-22 (PTPN22) gene polymorphisms. Four hundred thirteen children (141 with dental fluorosis and 198 boys) were enrolled from both historical endemic and non-endemic areas of fluorosis in Tianjin, China. The fluoride exposure levels, thyroid health indicators, and TSHR (rs2268458) and PTPN22 (rs3765598) polymorphisms were examined. Multiple logistic models were applied to evaluate the relationship between dental fluorosis and thyroid abnormalities. Children over 9 year old with dental fluorosis have lower FT4 and TGAb levels and thyroid volume and higher TPOAb levels (all P < 0.05). In overall participants, children with dental fluorosis were more likely to have thyroid antibody single positive issues (adjusted P = 0.039) and less likely to have a goiter according to age or body surface area (age or BSA) (adjusted P = 0.003); In the TSHR (rs2268458) SNP = CC/CT or PTPN22 (rs3765598) SNP = CC subgroup, dental fluorosis may cause thyroid antibody single positive (adjusted P = 0.036; adjusted P = 0.002); in the TSHR (rs2268458) SNP = TT or PTPN22 (rs3765598) SNP = CC subgroup, dental fluorosis may protect children from goiter (age or BSA) (adjusted P = 0.018; adjusted P = 0.013). Excessive fluoride may induce thyroid antibody single positive and reduce goiter in children. Heterogeneity exists in the relationship between excessive fluoride and thyroid antibody single positive or goiter issues across children carrying different TSHR (rs2268458) or PTPN22 (rs3765598) genotypes.
Keywords: Dental fluorosis; PTPN22; Polymorphisms; TSHR; Thyroid.
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