title: Comparison of radioimmunoassay and immunoradiometric assay for serum prostatic acid phosphatase.
abstract: We have compared the laboratory performance of immunoradiometric (IRMA) and radioimmunoassay (RIA) methods developed in this laboratory for measurement of serum prostatic acid phosphatase (PAP). The IRMA utilizes a radiolabelled mouse monoclonal anti-PAP and a solid phased rabbit polyclonal anti-PAP. The same rabbit antibody is used in the RIA. The IRMA shows excellent precision over a much wider working range (0.25-1000 micrograms/l) than the RIA (0.73-14.0 micrograms/l), and can be completed in 5 h, while the RIA requires 3 days. Levels in healthy males and in patients with benign prostatic hypertrophy are similar in both assays, upper limits of normal being 1.8 micrograms/l (IRMA) and 4.7 micrograms/l (RIA). The two assay methods correlate very well (r = 0.97) when PAP is measured in serum from prostatic cancer patients, although IRMA results are generally lower than those obtained by RIA. About 20% of patients with non-metastatic prostatic carcinoma had elevated serum PAP, whereas about 80% of those with metastatic disease had raised levels. The diagnostic efficiencies of the RIA and IRMA appeared similar. The value of the IRMA in follow-up and staging remains to be determined.
mesh_terms: D000469:Alkaline Phosphatase / Q000097:blood*; D004796:Clinical Enzyme Tests; D006801:Humans; D007158:Immunologic Techniques; D008297:Male; D009362:Neoplasm Metastasis; D011467:Prostate / Q000201:enzymology*; D011470:Prostatic Hyperplasia / Q000175:diagnosis / Q000201:enzymology; D011471:Prostatic Neoplasms / Q000201:enzymology; D011863:Radioimmunoassay; D012016:Reference Values; D013048:Specimen Handling
chemical_list: D000469:Alkaline Phosphatase