Seasonal and sex differences in the serum calcitonin levels of the rat.

Abstract

The serum levels of calcitonin, calcium and inorganic phosphate, and the urine concentrations of calcium and inorganic phosphate were measured in male and female rats in spring and in autumn. Significantly higher levels of serum calcitonin and calcium were found in spring than in autumn in both male and female rats. The calcium and inorganic phosphate contents of the urine were also significantly higher in spring than in autumn in both sexes. In addition to the seasonal variations, the serum level of calcitonin was higher in female than in male rats both in spring and in autumn.