Calcitonin reserve and the differentiated response to calcitonin in osteoporosis.

: The authors followed up the effect of calcium and calcitonin administration on phosphorus-calcium balance and on calcium retention, in correlation with the level of endogenous calcitonin, in 20 patients of perimenopause age (40-50 years), with radiologically confirmed osteoporosis. Calcium retention after loading with calcium gluconate (180 mg in i.v. injections) was determined before and after administration of salmon calcitonin (100 IV in i.m. injections). Two types of responses were noted. In a group of patients calcitonin administration determined a rise of calcium retention at the same time with the improvement of other biochemical parameters as well as a normal calcitonin response. The presence of high levels of circulating calcitonin 24h after loading with exogenous calcitonin demonstrated a slower inactivation rate of the hormone in these patients. The other group showed no positive response to calcitonin. The proposed test is a criterion for the selection of the patients with osteoporosis in view of chronic calcitonin treatment.