TESTOSTERONE PRODUCTION AND METABOLIC CLEARANCE RATES WITH VOLUMES OF DISTRIBUTON IN NORMAL ADULT MEN AND WOMEN

Abstract

ABSTRACT The complex aspects of androgen steroid metabolism make it important to investigate the relationship between the production rate of testosterone from analysis of a urinary metabolite and the production rate of steroid in the plasma. The plasma production rate of testosterone was estimated by the product of metabolic clearance rate (M. C. R.) and mean plasma concentration and this was compared with the urinary production rate by analysis of specific activity of a urinary metabolite, testosterone glucuronoside. The M. C. R. following single injection of tritiated testosterone calculated according to the method of Tait was 980 1/d S.D.±120 in 5 normal males and 760 and 840 1 in 2 females. The product M. C. R. and mean plasma testosterone indicates a plasma or inner pool production rate of 6.9 mg/d in normal male and maximum 0.8 mg/d in adult female. The urinary production rate was determined by injection of tritiated testosterone, enzyme hydrolysis of urine, chromatographic isolation of testosterone and its oxidized derivative, and determination of the cumulative specific activity. The urinary production rate was 6.5 mg S. D. ±1.9 in male and 1.9 mg/d S. D. ± 0.9 mg in normal female. 1 % of injected tracer was excreted as testosterone glucuronoside. The plasma production and urinary production rates in the male were quite similar, however the discrepancy in the female suggests that approximately 1 mg of testosterone precursor is converted to testosterone in a second compartment not in equilibrium with plasma testosterone.