[The hormonal response to hypercalcemic stimulation: the difference between male and female young people]

The aim of our study was to evaluate the pattern of response of thyroid Calcitonin (CT) secretory cells in young healthy people after specific stimulation. For this purpose, test of 60'' i.v. calcium infusion in a dose of 4 mg/Kg lean body mass was employed. Blood samples were taken at times-5', 0', 2', 5', 10', 15', and 30' after the infusion, to determine total Calcium (Ca), ionized calcium (Ca++) and CT concentrations. As a result, plasma CT increased significantly (f = 24.51, p less than 0.000001) in both sexes, while males showed stimulated CT values about double than the female ones: the difference was statistically significant throughout the test. In males too, we observed a strong and significant (r = 0.92, p less than 0.01) correlation between ionized calcium increases and CT responses. This correlation was found neither in males as regards total calcium, nor in females. In conclusion, our data confirm the higher CT secretion in males, indicating also a more constant pattern of response in this sex. Eventually, ionized calcium proves to be the real effective provocative stimulus for CT secretion.