Effect of Hyperthyroidism on Bone Turnover Markers and Bone Mineral Density Before and After Treatment With Antithyroid Drugs

Background and objectives Hyperthyroidism is a catabolic state with increased bone remodeling. Bone turnover markers (BTMs) and bone mineral density (BMD) may vary in patients with hyperthyroidism. The present study aimed to assess BTMs and BMD before and after antithyroid drug treatment in patients with hyperthyroidism. Methods This prospective observational study was conducted at a single tertiary care center from 4th November 2022 to 30th June 2024. Eighty-four newly diagnosed patients with hyperthyroidism, comprising men aged 18-65 years and premenopausal women aged >18 years, were enrolled. Of the 84 enrolled patients, 67 completed the follow-up and were analyzed. Sixty-five age-, sex-, and BMI-matched euthyroid subjects served as controls. BTMs, including procollagen type 1 N-propeptide (P1NP) and C-terminal cross-linked telopeptide (CTX), and BMD were assessed in all cases and controls. Carbimazole was initiated in all cases, and three months after achieving euthyroidism, BTMs were reassessed. BMD was assessed after one year of achievement of euthyroidism. Results Out of 67 hyperthyroid patients, 51 (76%) had Graves' disease, 11 (16%) had toxic multinodular goiter, and five (8%) had toxic adenoma. Serum P1NP and CTX levels were significantly higher in cases compared to controls (P-value < 0.001 for both). BMD at the lumbar spine and neck of femur (NOF) was significantly lower in cases (P- value < 0.001 for all comparisons). Following carbimazole treatment, the median paired changes in P1NP and CTX levels were -143 ng/mL and -0.71 ng/mL, respectively. BMD increased by 10.18% at the lumbar spine, 12.42% at the right NOF, and 11.09% at the left NOF. Conclusions Patients with hyperthyroidism exhibited significantly lower BMD with increased BTMs. Treatment with carbimazole was associated with a decrease in BTMs and incomplete recovery of BMD at one year of euthyroidism.