The metabolic clearance rate (MCR) and blood production rate (BP) of
testosterone (T) and
dihydrotestosterone (DHT), the conversion of plasma
testosterone to plasma
dihydrotestosterone, and the renal clearance of
androstenedione,
testosterone, and
dihydrotestosterone have been studied in man. In eight normal men, the MCR(T) (516+/-108 [SD] liters/m(2)/day) was significantly greater than the MCR(DHT) (391+/-71 [SD] liters/m(2)/day). In seven females, the MCR(T) (304+/-53 [SD] liters/m(2)/day) was also greater than the MCR(DHT) (209+/-45 [SD] liters/m(2)/day) and both values were less than their respective values in men (P < 0.001). In men the conversion of
testosterone into
dihydrotestosterone at 2.8+/-0.3% (SD) was greater than that found in females, 1.56+/-0.5% (SD) (P < 0.001). In five pregnant females the MCR(T) (192+/-36 [SD] liters/m(2)/day), the MCR(DHT) (89+/-30 [SD] liters/m(2)/day) and the conversion of
testosterone into
dihydrotestosterone (0.72+/-0.15%) (SD) were significantly less than the values found in nonpregnant women. In five females with
hyperthyroidism, the MCR for
testosterone and
dihydrotestosterone were similar to those observed in pregnant females, but the conversion of
testosterone into
dihydrotestosterone (2.78+/-1.7%) (SD) was greater, and similar to that found in men. In men the production of
dihydrotestosterone was 0.39+/-0.1 (SD) mg/day, 50% being derived from the transformation of plasma
testosterone. In women the production of DHT was 0.05+/-0.028 (SD) mg/day, only 10% coming from
testosterone. During pregnancy, the production of
testosterone and
dihydrotestosterone are similar to that in normal women. In three patients with
testicular feminization syndrome (an adult with
hyperthyroidism and two children) these two MCRs were greatly reduced compared to the normal females, but the conversion of
testosterone into
dihydrotestosterone was in the limits of normal male rangeIn the normal subjects the renal clearance of
androstenedione was greater than that of
testosterone and
dihydrotestosterone. Less than 20% of the
dihydrotestosterone and less than 10% of the
androstenedione in the urine is derived from the plasma
dihydrotestosterone and
androstenedione.