title: Immunochemical extraction and automated measurement of plasma creatine kinase MB isoenzyme and creatine kinase MB2 isoform.
abstract: Measurement of creatine kinase MB (CK-MB) and its isoforms CK-MB2 and CK-MB1 are now applied in the diagnosis of acute myocardial infarction (AMI). The most common approach for analysis includes RIA, IRMA, and electrophoresis, all of which may be time-consuming. This study examines determination of CK-MB and CK-MB2 by a rapid immunochemical extraction method followed by an automated measurement for both analytes. The automated method was sensitive to 2 U/L, linear to 180 U/L, and gave excellent interassay precision (< 10% CV). Interference studies indicated that bilirubin, hemolysis, and lipemia caused analytical problems as did the presence of high activities of other CK isoenzymes, notably CK-MM and CK-BB, requiring dilution of samples prior to analysis. Application of immunochemical extraction gave a reference interval of CK-MB (0-2.5 U/L) and CK-MB2 (0.1-1.4 U/L) for blood donors (20-60 years), peak levels for ruled-out AMI patients of CK-MB (0.5-7.3 U/L) and CK-MB2 (0.3-4.9), peak levels for ruled-in AMI patients of CK-MB (80-174 U/L) and CK-MB2 (80-155 U/L). Coronary artery bypass patients (n = 24) and all trauma patients (n = 14) also demonstrated elevations in CK-MB and CK-MB2, whereas only five of the trauma patients demonstrated increased CK-MB by IRMA. In patients (n = 7) having increased total CK and normal CK-MB by IRMA, the extraction assay for CK-MB and CK-MB2 yielded increased values in all patients. This new approach to CK-MB and CK-MB2 analysis can be performed within 30 minutes of sample receipt.
authors.affiliation: Department of Pathology and Laboratory Medicine, UCLA School of Medicine 90095-1732, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: McBride
authors.forename: S B
authors.initials: SB
authors.lastname: Schotters
mesh_terms: D000328:Adult; D001322:Autoanalysis; D001782:Blood Donors; D001026:Coronary Artery Bypass; D003402:Creatine Kinase / Q000097:blood* / Q000302:isolation & purification; D006335:Heart Injuries / Q000097:blood*; D006801:Humans; D007120:Immunochemistry / Q000379:methods*; D007527:Isoenzymes; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood*; D012015:Reference Standards; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D007527:Isoenzymes; D003402:Creatine Kinase