ABSTRACT
Radioimmunoassay (RIA) kits obtained from commercial sources were evaluated and compared with a standard counterimmunoelectrophoretic (CIE) assay for the measurement of prostatic acid phosphatase (PAP) in serum. None of the radioimmunoassays was found to be more sensitive than the CIE assay in detecting elevated serum PAP. Both immunoassays were somewhat more effective clinically in measuring prostatic specific acid phosphatase than an enzyme colorimetric assay. The results obtained by CIE agreed with the results obtained by RIA in 96 per cent of the tests. The number of positive results in patients with confirmed prostate adenocarcinoma increased with disease progression. The low number of positive tests in localized adenocarcinoma (Stages A and B) suggests that neither the CIE nor any RIA procedure is useful for screening unselected populations for adenocarcinoma of the prostate.