Comparison of various assay systems for prostate-specific antigen standardization

To avoid confusion between serum prostate-specific antigen (PSA) values among various assay systems, clinical studies on the possibility of conversion among detection values were performed. The assay kits used for the PSA comparisons were MARKIT-F PA, MARKIT-M PA, EIKEN PA, PA test WAKO, Ball ELSA PSA, E-Test Tosoh II PA, PROS-CHECK PSA, DELFIA PSA and TANDEM-R PSA. Using each kit, the standards attached to each assay system were detected, and 142 sera samples from benign hypertrophies or prostate cancers were assayed for serum PSA values. By detecting the standards for each kit, slopes were obtained which were almost identical to those obtained from original assay system. The coefficients of correlation among the PSA detection systems, using patients' sera, were very high, and linear regression lines were also obtained. The results suggest that almost identical serum PSA values may be detected either by multiplying by a coefficient to bring it to the standard or using the conversion formula.