[Prostate-specific antigen. Interpretation of the results in relation to the sampling method]

The authors compare the two prostate specific antigen assay methods most widely used in France. The first method (RIA Baxter) uses an isotope marker (Iodine 125), the other (EIA Biotrol) uses an enzymatic marker (alkaline phosphatase). Prostate specific antigen was assayed by means of these two techniques in two groups of patients: one group of 49 men considered to be free of any prostatic disease, recruited from blood donors; another group of 89 male patients in whom a prostate specific antigen assay was performed prospectively at the first urology outpatients visit. The two prostate specific antigen assay techniques gave different results, but the values obtained by these two methods were not discordant. It is therefore possible to define a coefficient of proportionality of 1.45 regardless of the prostate specific antigen concentration or the urological disease considered (EIA Biotrol x 1.47 = RIA Baxter).