SUPPRESSION OF BONE-RESORPTION IN EARLY POSTMENOPAUSAL WOMEN BY INTRANASAL SALMON-CALCITONIN IN RELATION TO DOSAGE AND BASAL BONE TURNOVER

In the present study, we assessed the ability of increasing doses of i ntranasal calcitonin to suppress urinary deoxypyridinoline cross-link (DPD), a specific biochemical marker of bone resorption, in early post menopausal women. Subjects consisted of 30 healthy Thai women within 5 years of postmenopause, randomly assigned to 50, 100, or 200 IU of in tranasal calcitonin 5 days/week for 3 months. Calcium supplementation by calcium carbonate capsules at 750 mg of elemental calcium per day w as given to all subjects. Twenty four-hour urine for DPD and creatinin e assays was collected at baseline, 1 month, and 3 months after treatm ent. All DPD values were corrected with urinary creatinine before anal yses. Data were expressed as mean +/- SEM. DPD decreased significantly 1 month after intranasal calcitonin treatment (P < 0.01). However, at 3 months, DPD increased when compared with the values at 1 month (P < 0.01), suggesting that there may be a reduction in the suppression of bone resorption after prolonged calcitonin therapy. Using a stepwise multiple regression model to address whether dosage and DPD at baselin e influence the response to intranasal calcitonin, it was found that D PD suppression after intranasal calcitonin was not related to dosage b ut was strongly associated with baseline DPD (P < 0.0001). Suppression of bone resorption in early postmenopausal women by intranasal calcit onin is determined more by the state of bone turnover at baseline than the dosage of calcitonin.