Impact of chronic dialysis on serum PSA, free PSA, and free total PSA ratio: Is prostate cancer detection compromised in patients receiving long-termdialysis?

Objectives. The increased incidence of malignancy tie, prostate cancer) in patients with end-stage renal failure is well known. However, little is kno wn of the impact of hemodialysis and various membrane types on total and fr ee prostate-specific antigen (PSA). We prospectively studied the impact of high- and low-flux dialysis membranes and kidney function on total PSA (tPS A), free PSA (fPSA), and free/total PSA ratio (f/t PSA). Methods. A total of 149 men were included. tPSA, fPSA, and f/t PSA were mea sured before and immediately after dialysis with high-flux (n = 101) and lo w-flux (n = 48) membranes in the serum and in the dialysis ultrafiltrate. A multivariate analysis of the impact of kidney function and age on the rate of change of all parameters was performed. Results. Overall, a significant decrease of fPSA (from 0.49 +/- 0.3 to 0.35 +/- 0.5 ng/mL, P <0.0001) and f/t PSA (from 45 +/- 19% to 38 +/- 13%, P <0 .0001) and a nonsignificant decrease in serum tPSA were observed. However, fPSA (from 0.51 +/- 0.5 to 0.27 +/- 0.3 ng/mL, P <0.0001) and f/t PSA (from 47 +/- 19% to 31 +/- 18%, P < 0.0001) decreased significantly in high-flux membranes only. The ultrafiltrate contained 100% fPSA in high-flux membran es and no fPSA in low-flux membranes. Age, serum creatinine, blood urea nit rogen, and dialysis evaluation parameters (Kt/V) had no impact on correlati on with changes in tPSA and fPSA. Conclusions. tPSA molecules do not pass high- and low-flux membranes; fPSA passes high-flux membranes only. The nonsignificant decrease of tPSA is due to adsorption to both dialysis membranes. Although tPSA can safely be used to screen patients on dialysis, independently from the dialysis procedure and membrane, fPSA and f/t PSA are only reliable with low-flux membranes. F inally, we can state that the fPSA is most probably cleared through the kid neys by glomerular filtration. UROLOGY 53: 1169-1174, 1999. (C) 1999, Elsev ier Science Inc. All rights reserved.