The precise mechanisms and extent of alterations in gonadotropins, sex steroids, and SHBG in hyperthyroidism have not been established; however, given the higher prevalence of menstrual abnormalities and anovulatory cycles in hyperthyroid women [152], it is conceivable that hyperthyroidism exerts its influence both centrally and peripherally. This evidence concerns the gene SHBG and hyperthyroidism.