Tracer studies of the fate of steroid hormones in the baboon

Urinary and fecal excretion of steroids has been studied by administration of tracer amounts of 4- 14C-labelled testosterone, hydrocortisone, estradiol-17β and progesterone in sets of four baboons differing in age, sex and physical condition. It was found that radioactivity following the administration of testosterone and hydrocortisone was excreted in the urine within 2 days, with 66.0–83.1% on the first day. The urinary radioactivity following estradiol-17β administration was lower on the first day as compared to testosterone and hydrocortisone; the total recovery in 4 days was 54.1–77.5%. Progesterone and its metabolites were eliminated even more slowly; in 4 days 33.5–41.3% of the radioactivity was excreted in the urine and 13.9–17.1% in the feces. The excreted radioactivity was almost entirely in conjugated form and appeared to show consistent patterns which were similar to that of man but differed from that of rodents.