Effect of oral anti-thyroid therapy on bone density in premenopausal women with endogenous subclinical hyperthyroidism

Subclinical endogenous hyperthyroidism is a fairly common disorder particularly in iodine deficient regions. There is controversy about adverse effects of this disorder on bone density in pre-menopausal women. The aim of this study was to determine the effect of oral anti-thyroid therapy on bone density in pre-menopausal women with subclinical endogenous hyperthyroidism. This randomized clinical trial included 30 premenopausal women (age range between 19 and 50 years) who had subclinical endogenous hyperthyroidism for at least 6 months. Thyroid function tests were performed in Kurdistan nuclear medicine center. The participants were randomly divided into two equal groups. Fifteen patients remained euthyroid for 1 year after receiving methimazole. Fifteen patients with subclinical hyperthyroidism were considered as control group and received no treatment for 1 year. Bone mineral density of the femoral neck and L2-L4 vertebrae were measured by DXA method at the beginning and 1 year after the study in both groups. The data were introduced into SPSS software and analyzed by X2 and t-tests. The risk factors for osteoporosis were not significantly different in both groups. Mean values for femoral neck and lumbar vertebral bone mineral density had decreased by 1.3% and 0.96% respectively in the treated group. But no statistically significant differences were detected before and after treatment (P value = 0.209 for femoral neck, P value = 0.432 for lumbar vertebrae). In the control group, mean values of the femoral neck bone and lumbar vertebral mineral density had also decreased by 2.1% and 1.0%, respectively, which did not show any significant difference after one year (P value = 0.069 for femoral neck, P value = 0.363 for lumbar vertebrae). Our findings showed that subclinical endogenous hyperthyroidism in premenopausal women in the short term had no adverse effect on bone density and treatment of this disorder with methimazole had no beneficial effect on bone mineral density in these patients.