SERUM N-TERMINAL OSTEOCALCIN IS A GOOD INDICATOR FOR ESTIMATING RESPONDERS TO HORMONE REPLACEMENT THERAPY IN POSTMENOPAUSAL WOMEN

To estimate the response to hormone replacement therapy (HRT) qv bone metabolic markers, 36 patients with postmenopausal osteoporosis or ost eopenia were studied to assess the correlation between percent baselin e changes in lumbar bone mineral density (BRID) after 12 months and th ose in various bone metabolic markers after 3, 6, and 12 months of HRT . All the patients were treated with 0.625 mg of conjugated estrogen a nd 2.5 mg of medroxyprogesterone per day and continued for 12 months. BMD was significantly increased up to 4.19 +/- 0.87% after 6 months an d 4.93 +/- 1.27% after 12 months of HRT (p = 0.0001 by analysis of var iance). In accordance with this, changes in the levels of osteocalcin (p = 0.011), alkaline phosphatase (p = 0.0001), N-terminal osteocalcin (p = 0.0001), urinary excretion of pyridinoline/Cr (p = 0.0001), and deoxypyridinoline/Cr (p = 0.0001) were significantly decreased, respec tively, Among these bone metabolic markers, only the change in the ser um N-terminal osteocalcin at 3 months (r = 0.557, p = 0.0022), at 6 mo nths (r = 0.470, p = 0.0184), and at 12 months (r = 0.535, p = 0.0061) significantly correlated with the change in BMD 12 months after HRT. The elution profiles of immunoreactive osteocalcin-related molecules i n serum fractionated qv reverse-phase high performance liquid chromato graphy revealed that the N-terminal fragment as well as the intact ost eocalcin molecule decreased after 3 months of HRT, These results demon strate that N-terminal osteocalcin is a suitable predictor for estimat ing good responders to HRT in postmenopausal women.