EFFECT OF HEMODIALYSIS ON TOTAL, FREE AND PERCENT-FREE PROSTATE -SPECIFIC ANTIGEN

Objective: To evaluate the effect of hemodialysis on serum total, free and percent free prostate specific antigen (PSA). Patients and Methods: This study included 34 men with chronic renal failure (mean age 58 years, range 45-80) who received hemodialysis with low flux membranes. We measured pre-and post-hemodialysis total PSA (tPSA), free PSA (fPSA) and hematocrit (Htc) at one dialysis session. Additionally, the percent fPSA to tPSA (f/t PSA) ratio was calculated before and after dialysis. Htc was measured before and after dialysis to determine the degree of hemoconcentration and the correlation between PSA levels and Htc. Results: There were statistically significant increments in the mean values of tPSA (pre -dialysis 1.2, post-dialysis 1.4 ng/ml) and f/tPSA ratio (pre-dialysis 28.2%, post dialysis 35.2%). In addition, a significant increase in Htc was noted after dialysis. The mean pre-dialysis fPSA was 0.4 and the post -dialysis value was 0.43 ng/ml (difference not statistically significant). The degree of hemoconcentration was not statistically correlated with the elevation in the values of tPSA, fPSA and f/tPSA Conclusions: Although the increment in tPSA was statistically significant, it was not clinically meaningful. The most likely explanation for the increment in tPSA and fPSA after hemodialysis is volume contraction, and hemodialysis with low flux membranes appears to have no effect on PSA clearance. Pre-dialysis determination of tPSA probably provides no false positive results. Therefore, we advocate that serum PSA determination is done in conjunction with digital rectal examination (DRE) and/or transrectal ultrasonography (TRUS) in patients on dialysis, especially those who are candidates for renal transplantation, to rule out prostate cancer.