SKELETAL RESPONSIVENESS TO THYROID-HORMONE IS NOT ALTERED AT MENOPAUSE

Hyperthyroidism is characterized by increased bone turnover and resorp tive activity, Similar changes in remodeling are seen after menopause, To study the role of thyroid hormone in the menopause-related changes in bone metabolism, we investigated thyroid status and the sensitivit y of bone to thyroid hormone in 14 premenopausal and 15 early postmeno pausal women, Triiodothyronine (T-3) was administered to the two group s as 20 mu g doses three times daily for 7 days, The skeletal response was assessed by monitoring bone alkaline phosphatase (BAP), osteocalc in (BGP), pyridinium crosslinked telopeptide domain of type I collagen (ICTP) in serum and urinary excretion of hydroxyproline (OHP), pyridi noline (PYR), and deoxypyridinoline (DPR) at days 0, 8, 15, and 57, Th e early postmenopausal women had increased bone turnover as reflected in sBAP (p < 0.05), sBGP (p < 0.05), and uOHP (p < 0.01) when compared with premenopausal controls, T-3 stimulation of early postmenopausal and premenopausal women significantly increased the markers of bone re sorption: sICTP (56% vs, 44%), uOHP (45% in both groups), and UPYR (83 % vs, 17%) without any significant differences between groups, Of the formative markers, only sBGP increased significantly after stimulation (34% vs, 41%), but both sBGP and sBAP displayed significant increases from days 15 to 57, Thus, stimulation with thyroid hormone results in an immediate stimulation of ongoing bone formation and bone resorptio n, but also initiation of new remodeling which, after 8 weeks, reached the formative phase, PTH decreased (p < 0.01) in both groups but seru m calcium and serum phosphate were unaltered, In conclusion, menopause is not characterized by altered levels of thyroid hormones or altered skeletal responsiveness to thyroid hormones. (C) 1996 by Elsevier Sci ence Inc.