Metabolism of Progesterone-4-C¹⁴in Young and Elderly Men

Abstract

Recovery of radioactivity of the administered dose of progesterone-4-C14 in the urine was 54 % for the young and 44 % for the elderly subjects, and in the neutral extract, 32 and 25 %, respectively. Young men excreted an average of 14 % of the radioactive dose as pregnanediol (P-diol), elderly men 10%. Both the excretion of P-diol and the secretion rate of progesterone expressed as mg/day or as mg/g creatinine were significantly less in elderly than in young subjects. The contrast between the age-related changes observed in progesterone and cortisol metabolism is discussed.