Bone changes in hyperthyroidism--a preliminary study.

Thyrotoxicosis may cause osteopenia and lead to increased risk of fractures. From July 1988 to March 1989, 88 hyperthyroid patients and 65 age, sex matched normal controls were enrolled for lumbar spine bone mineral density (BMD) study. Significantly lower BMD values can be found in premenopausal hyperthyroid women (1.233 gm/cm2 vs 1.317 gm/cm2, p less than p less than 0.05). In the group of thyrotoxicosis, no linear correlation can be found between BMD and the degree of hyperthyroidism (N = 84, r = 0.01 and N = 74, r = 0.054 as comparing BMD to T4 and T3, respectively). After treatment with antithyroid drugs (ATD) for 3 months, BMD did not change significantly (1.258 gm/cm2 vs 1.242 gm/cm2, p = 0.02) in the hyperthyroid patients. Therefore, premenopausal hyperthyroid women have lower BMD than premenopausal euthyroid women. The treatment of hyperthyroidism after 3 months' course did not increase lumbar spine BMD.