The effect of calcitonin on biochemical markers and zinc excretion in postmenopausal osteoporosis.

OBJECTIVES: A double-blind, randomized, placebo-controlled trial was conducted in women with postmenopausal osteoporosis to evaluate effects on biochemical markers and urinary excretion of zinc (Zn) of calcitonin therapy.

METHODS: Patients were required to have a bone mineral density (BMD) of 2.5 S.D. or more below the young adult mean either at the postero-anterior lumbar spine or at the femoral neck. Subjects were eligible for our study if they were 50 years or older, with at least 5 years of menopause, and in good general health as determined by medical history and a routine clinical blood analysis. The patients were randomly assigned to receive intranasal salmon calcitonin (200 IU/day; 50 patients) or placebo (50 patients). All patients received supplemental calcium (1000 mg/day). Additionally, 40 age-matched, demographically similar, healthy postmenopausal women were also selected as controls. Measurements of cross-linked N-telopeptides of type I collagen (uNTx), osteocalcin (sOC), and urinary zinc concentration were done. All parameters were measured before therapy and again after 1, 3 and 6 months.

RESULTS: After 3 and 6 months of treatment, a higher decrease of most indices was observed in the calcitonin group. A statistically significant decrease occurred in the levels of sOC, uNTx and uZn after 3 and 6 months in patients receiving calcitonin therapy (P<0.05). Levels of sOC and uNTx in calcitonin group were significantly different after 3 and 6 months from both placebo and baseline values of calcitonin group (P<0.05). Levels of sOC, uNTx and uZn decreased about 40, 46 and 37%, respectively, in calcitonin group at 6 months after the start of treatment.

CONCLUSIONS: Our study suggests that values of uNTx, uZn and sOC were significantly lower in the patient group than those in control group and in postmenopausal women with osteopororsis, calcitonin reduces the concentrations of uNTx, uZn and sOC.