TRACER STUDIES OF THE ABSORPTION AND FATE OF STEROID HORMONES IN MAN 1

Abstract

The absorption, distri-bution, biochemical alteration and excretion of steroid hormone metabolites were studied in man following the oral or parenteral administration of labeled hydrocortisone, cortisone, acetate, corti-costerone, and testosterone. In studies on subjects in whom the thoracic duct was cannulated, it was established that the portal system is the route through which orally administered hydrocortisone and testosterone are absorbed. There was no appreciable excretion of metabolites of these steroid hormones in the bile of patients with complete biliary fistulas. The absence of an enterohepatic circulation in the human represents a significant species difference when compared with the rodent where biliary excretion is obligatory. Labeled steroid metabolites appear in the urine in the game quantities and at similar rates following oral or intravenous administration of hydrocortisone. The lack of biological effect following the oral administration of testosterone compared with the parenteral route was shown to be unrelated to the rate or extent of absorption since the excretory pattern was the same in male and female subjects following either oral or intravenous labeled testosterone. I n spite of the extremely rapid excretion of the major portion of the steroid hormones studied, it was shown unequivocally that virtually all of the excretory products represented chemically altered metabolites of the original hormone. These studies indicate that the reactions in which the hormone participates in order to exert its unique physiological activity occur within a short time following either the secretion or introduction of the steroid into the body.