Clinical and analytical evaluation of different methods for measurement of creatine kinase isoenzyme MB

We evaluated the clinical and analytical performance of the new immunochemiluminometric assay (ICMA; Ciba Corning) for measurement of creatine kinase isoenzyme MB (CK-MB), and compared it with three other methods: immunoradiometric assay (IRMA; International Immunoassay Labs); immunoinhibition assay (Seradyn); and an immunoinhibition/column method (Du Pont). Intra-test precision for all kits was good. We evaluated 32 patients' samples by all four methodologies. Only one of the four methods (aca, Du Pont) showed evidence of linearity. Efficiency in the diagnosis of myocardial injury in our study ranged from 53% (Seradyn) to 96% (Du Pont). We evaluated serial specimens from 20 separate patients by the IRMA and the ICMA to determine whether myocardial injury could be diagnosed earlier by the ICMA. In patients with acute myocardial infarction, the ICMA displayed positive values earlier and longer than the IRMA, suggesting that the ICMA is suited for screening for myocardial damage in hospitalized patients.