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 calc ium was applied. The control group consisted of 35 postmenopausal wome n distributed according to time since menopause. Biochemical and hormo nal evaluations of calcium metabolism were performed at the start of t reatment and after 6, 12, 18 and 24 months of treatment. Mean serum os teocalcin 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 un treated women during the first 12 postmenopausal months. Mean 24-h hyd roxyproline excretion decreased during the first 12 months of therapy but increased in the subsequent 6 months. The observed rise in serum o steocalcin concentration and urinary hydroxyproline excretion during t he 2nd year of treatment with calcitonin was accompanied by a signific ant rise in serum calcitonin level. No significant differences in seru m calcium, phosphorus, alkaline phosphatase or parathormone concentrat ion, or urinary calcium excretion, were observed between treated and u ntreated women during the 24-month period. This study shows that 12 mo nths' treatment with intranasal salmon calcitonin decreases bone resor ption in early postmenopausal women, while bone formation remains unch anged. Longer treatment with intranasal salmon calcitonin, however, se ems to be ineffective, most probably due to secondary resistance to ca lcitonin. This justifies intermittent treatment schedules: the most ap propriate ones have yet to be established.