Kinetics of testosterone, dihydrotestosterone (DHT) and 5alpha-androstane-3alpha,17beta-diol (3alpha-diol) were studied in 7 elderly healthy men (ages 61 to 80 years) with benign prostatic hyperplasia (BPH). Clearance rates were determined by the constant infusion technique with labeled testosterone and DHT. Metabolic clearance rate (MCR), conversion ratio (CR), the transfer constants (rho) and production rates (PB) were calculated. Plasma androgens were measured by specific radioimmunoassay. Plasma testosterone was 516 +/- 314 (SD) ng/dl, plasma DHT was 74.6 +/- 19.6 (SD) ng/dl and plasma 3alpha-diol was 16.4 +/- 4.1 (SD) ng/dl. An elevated DHT level in elderly men with BPH wasconfirmed. MCRT was 620 +/- 65 (SD) liter/day and MCRDHT was 393 +/- 50 (SD) liter/day. Both MCRT and MCRDHT in elderly men were significantly lower than in young men. PBT was 3.2 +/- 2.1 (SD) mg/day and PBDHT was 291 +/- 87 (SD)migrogram/day. PBDHT was the same in elderly and young men. DHT production is maintained in elderly men despite reduction of testosterone production. From the data, it was claculated that in contrast to young men where greater than 80% of blood DHT is from secreted testosterone, over 50% in elderly men is derived from secretion or production of DHT by the testis or even more likely the prostate.

The splanchnic extraction and interconversion of testosterone and dihydrotestosterone (DHT) were studied in 7 healthy men (ages 29-46 years) undergoing cardiac catheterization. During a constant infusion of [1,2-3H]testosterone and [4-14C]DHT, the arterial and hepatic vein blood samples were taken and radioactive and non-radioactive testosterone and DHT were determined. Metabolic clearance rate (MCR), splanchnic extraction (SE), splanchnic clearance (SC), extrasplanchnic clearance (ESC), transfer constant in blood (T-DHT rhoBB) and transfer constant across the liver (T-DHT rhoSB) were calculated. The MCRT was 952 +- 172 (mean +- SD) 1/day and MCRDHT was 764 +/- 67 1/day in agreement with data from non-catheterized subjects. SET was 68.8 +/- 7.1% (mean +/- SD) and SEDHT was 37.6 +/- 5.9%. SET was significantly greater than SEDHT (P less than 0.001). The calculated SCT and ESCT were 638 +/- 112 (mean +/- SD) 1/day and 314 +/- 190 1/day, respectively. SCDHT and ESCDHT were 343 +/- 95 (mean +/-SD) 1/day and 421 +/-105 1/day, suggesting that a major fraction of testosterone is metabolized in the splanchnic organs and a higher fraction of DHT is metabolized in extrasplanchnic organs. In the interconversion study, overall conversion of testosterone to DHT in blood (T-DHT rhoBB) was 4.0 +/- 0.6% (mean +/- SD). No evidence for a net appearance of DHT by either mass or specific activity analysis in hepatic vein blood was observed in any infusion leading to the conclusion that the overall contribution of testosterone to circulating DHT from the liver (T-DHTrhoSB) was undetectable. This work indicates that conversion of testosterone to DHT occurs entirely in extrasplanchnic tissue in man.

The incidence of macrosomic infants weighing 5,000 g or more is rare. We experienced a case of nondiabetic macrosomia, in which the fetus weighed more than 5,000 g. The newborn was diagnosed as having Simpson-Golabi-Behmel syndrome. We discuss antenatal ultrasonographic findings in the case.