Relative deficiency of plasma-calcitonin in normal women.

A new radioimmunoassay technique was used to measure plasma-calcitonin in normal subjects. Plasma-calcitonin concentrations in women were less than 25% of those in men, and were often undetectable. However, during pregnancy or administration of the oestrogen-progestagen contraceptive pill, plasma-calcitonin equalled or exceeded male concentrations. These findings are consistent with an effect on calcitonin production of normal male testosterone concentrations and concentrations of the sex steroids during pregnancy. Calcitonin may protect the skeleton during calcium stress. Further, although it is unknown whether a deficiency of the hormone plays a role in postmenopausal osteoporosis, this is now a definite possibility which requires urgent investigation.