Whether biochemical markers can predict improvement in reduced bone mineral density (BMD) associated with thyrotoxicosis in unclear. We investigated the relationship between serum osteocalcin (OC), bone-specific alkaline phosphatase (b-ALP), serum deoxypyridinoline (Sdpd) and pyridinoline (Spyr), 24-hour urinary deoxypyridinoline (Udpd), and BMD in 17 thyrotoxic patients during 1 yr of treatment. Coinciding with euthyroidism at 4-8 weeks, there was a peak in b-ALP and OC and a prompt fall into the normal range in Udpd and Sdpd, but not Spyr, levels. Mean b-ALP continued to be raised at week 52 when it was inversely correlated with BMD. Mean BMD rose approximately 6%, P < 0.01, over 1 yr. Coupling indices were calculated as a measure of bone balance and, at diagnosis, was [minus4.26 in favor of bone resorption and rose with treatment in favor of bone formation: weeks 2: -0.23; 4: +4.01; 8: +4.37; 12: +4.44; 24: +2.32; and 52: +1.56. Bone turnover is balanced within 2 weeks of starting treatment for thyrotoxicosis. Udpd accurately indicates thyrotoxic bone resorption. Serum b-ALP indicates continuing bone formation and, at 1 yr, may provide a marker for low BMD. OC, Sdpd, and Spyr are less sensitive in documenting bone remodeling during treatment of thyrotoxicosis.
Adult Antithyroid Agents