The Metabolism and 24-Hour Plasma Concentrations of Androsterone in Man

A radioimmunoassya for free androsterone permitting facile analysis of plasma taken at 20 min intervals over 24 h has revealed a curve of varying concentrations which formed a pattern similar to curves of cortisol and dehydroisoandrosterone, boht bein primary adrenal secretory products and the latter being the major precursor of androsterone. The mean of the average 24 h concentrationof androsterone in men was 55 +/- 14 ng/dl (n = 8). Such temporally related behavior requires rapid production and removal of both 17-ketosteroids, processes which have been confirmed by tracer studies where it has been shown that in a two compartment system, androsterone has a t1/2 of 25 +/- 9 min for the fast component and metabolic clearance rate of 4050 +/- 1315 L per day (n = 10). The data are in accord with an approximate production rate of androsterone which is consistent with values reported for its urinary excretion.