Reference Ranges for the Concentrations of Total and Complexed Plasma Prostate-Specific Antigen and Their Ratio in Patients with Benign Prostate Hyperplasia

Abstract

To establish the normal distribution and reference ranges of complexed and total prostate-specific antigen (PSA) and the complexed-to-total PSA ratio according to the age of the patients, so that PSA can be used to distinguish between prostate cancer and benign prostate hyperplasia (BPH). Using specific ELISAs, total PSA and PSA complexed to alpha 1-antichymotrypsin (complexed PSA) were determined in 237 BPH patients, 160 with histologically confirmed BPH and 77 in whom prostate cancer was excluded by digital rectal examination, transrectal ultrasound and total PSA measurement. Both total and complexed PSA correlated with patient age (r = 0.424 and r = 0.379, p < 0.0001, respectively). However, no correlation was found between the complexed-to-total PSA ratio and age (r = 0.026, p > 0.2). The mean complexed-to-total PSA ratio for the 237 BPH patients was 0.69 +/- 0.11, and only 23 had a ratio > 0.8. These results show that the cut-off point of 0.8 established for the complexed-to-total PSA ratio is the same for men of all ages, and that the use of this ratio may avoid many negative prostate biopsies, confirming that PSA: alpha 1ACT is a potential marker for differential diagnosis of prostate carcinoma and BPH.