Prostate specific antigen is metabolized in the liver.

PURPOSE: The site of metabolism of prostate specific antigen (PSA) was determined. MATERIALS AND METHODS: In a prospective study, during clinically indicated left and right heart catheterizations for various cardiac diseases in 12 men (mean age 62.5 +/- 8.3 years, standard deviation), selective blood samples were obtained from the infra-renal, infra-hepatic and supra-hepatic inferior vena cava, renal vein, superior vena cava, pulmonary artery and femoral artery. Mean PSA concentration was calculated for all vascular sites. Using a paired Student t test, the mean difference between the afferent and efferent PSA concentrations across the renal, hepatic, pulmonary and pelvic circulation was calculated. RESULTS: The hepatic gradient between the infra-hepatic and suprahepatic inferior vena cava showed the greatest decrease (0.11 +/- 0.16 ng./ml. or 8.3%) in PSA concentration and was statistically significant (p = 0.04). A smaller decrease across the pulmonary circulation was statistically insignificant. No decrease in the PSA concentration was noted across the renal circulation. The PSA concentration increased significantly (0.19 +/- 0.18 ng./ml. or 16.3%, p = 0.003) across the pelvic circulation, confirming the release of PSA from the prostate. CONCLUSIONS: PSA is released from the prostate. The kidneys and lungs do not have a significant role in elimination of PSA, and the liver appears to be the most likely site of its metabolism. Although our sample size is small and the PSA range is narrow, our results strongly support these conclusions.

The impact of 5-alpha-reductase inhibitors on the number of prostatectomies for benign prostatic hyperplasia.

To determine the impact of a 5-alpha-reductase inhibitor on the need for surgical treatment of symptomatic benign prostatic hyperplasia (BPH) in clinical urologic practice, we retrospectively reviewed records of 794 patients treated with pharmacotherapy or surgery (or both). The number of transurethral resections of the prostate (TURPs) performed during the 30 months since introduction of finasteride was compared with the number performed during the 30 months before finasteride became available. The alpha-blockers doxazosin and prazosin were used during both times for the treatment of BPH. Of the 619 patients treated with drugs, 88.5% received finasteride for a mean of 249.6 days. The alpha-blockers, either alone or combined with finasteride, were prescribed for 11.5% of patients for a mean of 179 days. In the 30 months after the introduction of finasteride, 65 patients underwent TURP: 28 of these men had initially received drug therapy. In contrast, 138 TURPs were performed in the 30 months prior to the availability of finasteride. The use of a 5-alpha-reductase inhibitor as primary medical therapy for symptomatic BPH decreased the number of prostatectomies by 52.9% (65 vs 138). This observation warrants corroboration through additional prospective studies.