Creatine kinase 2 mass measurement: methods comparison and study of the matrix effect

Five different commercial immunoassays for the measurement of creatine kinase isoenzyme 2 mass concentration were compared using human plasma samples covering a wide range of creatine kinase 2 concentrations. The immunoassays studied differ in the detection systems, in the specificity of the antibodies and in the calibrators used. Intermethod comparison by regression analysis showed differences in the results of creatine kinase 2 mass concentration. The following ratios were deduced from the obtained equations: Elecsys=1.10xImmulite=1.20xIMx=1.26xACS:180=1.33xStratus. The commutability of different materials prepared by diluting purified human creatine kinase 2 in biological and synthetic matrices was studied using the different immunoassays in comparison with human plasma specimens. Almost all the materials tested were not commutable. Copyright (C) 1999 Elsevier Science B.V.