Calcitonin metabolism in senile (type II) osteoporosis.

The exact role of calcitonin (CT) in the pathogenesis of senile (Type II) osteoporosis remains unknown. Whole plasma calcitonin (iCT) and extracted monomeric calcitonin (eCT) basal levels, metabolic clearance rate (MCR) and production rate (PR) of iCT and eCT were measured in 41 postmenopausal women, including 14 hip fractures (OP II) and 27 healthy controls. No significant difference appeared for basal iCT levels between OP II (mean +/- SEM: 41.9 +/- 3.4 pg/ml) and controls (mean +/- SEM: 46.2 +/- 5 pg/ml). eCT basal levels were similar in OP II (mean +/- SEM: 5.42 +/- 0.5 pg/ml) and in controls (mean +/- SEM: 7.3 +/- 0.7 pg/ml). MCR were similar in the two groups. iCT PR were similar in OP II (mean +/- SEM: 17.2 +/- 1.5 micrograms/24 h) and controls (mean +/- SEM: 18.6 +/- 1.1 micrograms/24 h). No difference appeared between eCT PR in OP II (mean +/- SEM: 2.3 +/- 0.2 micrograms/24 h) and controls (mean +/- SEM: 3.2 +/- 0.3 pg/ml). From these data, no evidence appears that calcitonin might be one of the determinant factors in the pathogenesis of senile osteoporosis.