A LONGITUDINAL-STUDY OF MARKERS OF BONE TURNOVER IN GRAVES-DISEASE AND THEIR VALUE IN PREDICTING BONE-MINERAL DENSITY

Whether biochemical markers can predict improvement in reduced bone mi neral density (BMD) associated with thyrotoxicosis is unclear. We inve stigated the relationship between serum osteocalcin (OC), bone-specifi c alkaline phosphatase (b-ALP), serum deoxypyridinoline (Sdpd) and pyr idinoline (Spyr), 24-hour urinary deoxypyridinoline (Udpd), and BMD in 17 thyrotoxic patients during 1 yr of treatment. Coinciding with euth yroidism at 4-8 weeks, there was a peak in b-ALP and OC and a prompt f all 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 correla ted with BMD. Mean BMD rose approximately 6%, P < 0.01, over 1 yr. Cou pling indices were calculated as a measure of bone balance and, at dia gnosis, was [minus4.26 in favor of bone resorption and rose viith trea tment 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 indic ates thyrotoxic bone resorption. Serum b-ALP indicates continuing bone formation and, at 1 yr, may provide a marker for low BMD. OC, Sdpd, a nd Spyr are less sensitive in documenting bone remodeling during treat ment of thyrotoxicosis.