Determination of the site of metabolism of total, free, and complexed prostate-specific antigen

Objectives. To determine the site of metabolism of total prostate-specific antigen (tPSA), free PSA (fPSA), and complexed PSA (cPSA). Methods. A total of 20 male patients, 50 years old or older, having a clinical indication for left and right heart catheterization were enrolled in this study. Selective blood samples were obtained from the infrarenal, infrahepatic, and suprahepatic inferior vena cava, renal vein, hepatic vein, superior vena cava, pulmonary artery, and femoral artery. cPSA concentration was accepted as the difference between tPSA and fPSA concentrations. Results. We found that tPSA and fPSA concentrations in the infrarenal inferior vena cava were significantly higher than in the systemic artery. There was no significant difference between the systemic artery and the infrarenal inferior vena cava for cPSA concentration. Although fPSA concentration decreased significantly across the renal circulation, the decreases in cPSA and tPSA concentrations were statistically insignificant. In the hepatic circulation, we found that tPSA, fPSA, and cPSA concentrations were significantly decreased. No decrease in tPSA, fPSA, and cPSA concentrations were noted across the pulmonary circulation. Conclusions. Our results indicate that fPSA and tPSA are released into serum from the prostate but the prostate may not have a significant role in complex formation of PSA. In addition, the liver has a significant role in the elimination of tPSA, fPSA, and cPSA. By contrast, the kidneys have a significant role only in the elimination of fPSA. We also found that the lungs did not have a significant role in the elimination of tPSA, fPSA, or cPSA. UROLOGY 52: 470-473, 1998. (C) 1998, Elsevier Science Inc. All rights reserved.