Purpose: The aim of this study was to investigate the relationship between percent-free prostate-specific antigen (PSA) and estimated glomerular filtration rate (GFR) in men whose PSA level was 4-10 ng/ml with biopsy-proven prostate status.
Methods: Between 2004 and 2010, the medical records of 495 cases (404 cases without prostate cancer and 91 cases with prostate cancer) who underwent prostate biopsy were reviewed and their GFR was calculated using the Cockcroft-Gault equation, adjusted for body surface area. Correlation and multivariate regression analyses were conducted among percent-free PSA, body mass index, prostate size, and GFR in patients with and without prostate cancer, respectively.
Results: The mean patient age was 64.6 years, and the median PSA and free PSA were 5.64 and 0.87 ng/ml. The mean GFR was 61.02 mL/min/1.73 m2, and mean percent-free PSA was 18.9%. Correlation analysis showed that percent-free PSA was correlated with GFR, age, and prostate size in the non-cancer cohort and correlated with only prostate size in the cancer cohort. Multivariate regression analysis showed that percent-free PSA was influenced by GFR (p < 0.001) and prostate size (p < 0.001) independently in the non-cancer cohort, while only by prostate size (p = 0.008) in the cancer cohort.
Conclusions: Percent-free PSA has a negative relationship with GFR in the benign prostate group, while it does not in the prostate cancer group. Screening with current cutoff value of percent-free PSA can be applied to the patients with impaired renal function.