Acute Effects of Calcitonin Nasal Spray on Serum C-telopeptide of Type 1 Collagen (CTx) Levels in Elderly Osteopenic Women with Increased Bone Turnover
Salmon calcitonin is a potent inhibitor of osteoclastic activity. The effect of calcitonin in elderly women with high bone turnover at higher risk of developing osteoporosis has not been studied. To investigate acute effects of calcitonin treatment on bone resorption markers in elderly women, we conducted a randomized trial in women >65 years of age with high bone turnover assessed as urinary N-telopeptide of type-I collagen (NTx) levels 1 SD higher than mean premenopausal levels, which was irrespective of bone density. A total of 98 elderly women were randomly assigned to receive either 200 IU calcitonin nasal spray (n = 75) with calcium (500 mg) and vitamin D (200 IU) or calcium and vitamin D (n = 23) alone for 6 months. Blood and urine samples were collected at 0, 2, 4, and 6 months and analyzed for urinary NTx and serum C-telopeptide of type-1 collagen (CTx). At baseline, mean age was 72.1 ± 4.7 (mean ± SD) in the calcitonin group and 72.2 ± 6 years in the control group. The spine and total hip BMD, serum PTH levels and urinary calcium/creatinine ratios were similar in both groups. Mean BMD was in the osteopenic range in both groups. Calcitonin treatment resulted in significant decreases in serum CTx levels, 2, 4 and 6 months after treatment as compared to baseline, and after 4 and 6 months as compared to controls. A maximum decrease from baseline of 33% was seen at 6 months. The urinary resorption marker, urine NTx, showed a significant decrease in the calcitonin group when compared to baseline only at the 6-month time point. Analysis of least significance change (LSC) showed that 70% of calcitonin patients were categorized as responders using serum CTx after 6 months of treatment. We conclude that 200 IU calcitonin effectively decreases bone resorption within 60 days of therapy, thus preventing further bone loss in elderly women who are at a high risk of developing osteoporosis.