Nevertheless, the association between SH and increased VF risk may be explained by: (1) The excessive levels of thyroid hormones at the upper limit of the normal range or above can lead to accelerated bone turnover, bone loss, and an increased risk of fractures [47] and (2) metabolic pathways for the role of exogenous and endogenous thyroid hormones differ, and endogenous STD may go undetected for many years because symptoms of STD are often nonspecific or asymptomatic [48]. This evidence concerns the gene TG and sexually transmitted disease.