The level of total prostate specific antigen (t-PSA) was determined by an immunoradiometric assay (IRMA) in sera of normal men, patients with BPH and patients with PCA.2- The level of PSA was determined in benign prostatic tissue homogenate and in cytosol of BPH tissue by IRMA.3- The prostate specific antigen density PSAD was estimated in patients with BPH and PCA