THE EFFECT OF INTRANASAL SALMON-CALCITONIN ON BIOCHEMICAL PARAMETERS OF BONE TURNOVER IN POSTMENOPAUSAL WOMEN

This study aims to evaluate the effect of intranasal salmon calcitonin on variables of bone metabolism in 12 postmenopausal women during 24 months of treatment. A treatment regime of 100 U of intranasal salmon calcitonin on alternate days and 1500 mg daily of oral elementary calcium was applied. The control group consisted of 35 postmenopausal women distributed according to time since menopause. Biochemical and hormonal evaluations of calcium metabolism were performed at the start of treatment and after 6, 12, 18 and 24 months of treatment. Mean serum osteocalcin concentration was unchanged during the 1st year of treatment but was significantly elevated during the 2nd year (p = 0.03 and p = 0.005 after 18 and 24 months, respectively) when compared to levels at 12 months. Similar elevation of osteocalcin levels was observed in untreated women during the first 12 postmenopausal months. Mean 24-h hydroxyproline excretion decreased during the first 12 months of therapy but increased in the subsequent 6 months. The observed rise in serum osteocalcin concentration and urinary hydroxyproline excretion during the 2nd year of treatment with calcitonin was accompanied by a significant rise in serum calcitonin level. No significant differences in serum calcium, phosphorus, alkaline phosphatase or parathormone concentration, or urinary calcium excretion, were observed between treated and untreated women during the 24-month period. This study shows that 12 months' treatment with intranasal salmon calcitonin decreases bone resorption in early postmenopausal women, while bone formation remains unchanged. Longer treatment with intranasal salmon calcitonin, however, seems to be ineffective, most probably due to secondary resistance to calcitonin. This justifies intermittent treatment schedules: the most appropriate ones have yet to be established.