CREATINE KINASE-MB ACTIVITY - CLINICAL AND LABORATORY STUDIES OF SPECIFIC IMMUNOCHEMICAL TECHNIQUE WITH OPTIMIZED ENZYMATIC ASSAY

  • 1 January 1983
    • journal article
    • research article
    • Vol. 13  (1) , 59-66
Abstract
A centrifugal analyzer method was developed for measuring the MB isoenzyme of creatine kinase (CK) (EC 2.7.3.2) in serum by use of a specific immunochemical technique that avoids interference from CK-BB and adenylate kinase. Enzymatic activity was measured kinetically at 30.degree. C with an optimized reagent containing creatine phosphate as substrate. The precision (CV [coefficient of variation]) of the assay was 5-12% day-to-day (n = 39). The reference interval was 0-3.5 U/l (n = 45). Patient samples without detectable CK-MB in a widely used electrophoretic assay contained up to 12 U/l of CK-MB by the new method. The new test was evaluated carefully in 99 patients consecutively admitted to the coronary care unit. Blood samples were obtained at frequent (4-8 h) intervals. All patients with acute myocardial infarction (n = 27) had peak CK-MB > 7 U/l and > 3.5% of total CK. The predictive value of this result was 94% for the diagnosis of infarction. Abnormal results were documented at the same times (.+-. 4 h) following infarction by the electrophoretic and immunochemical techniques. Guidelines were evolved for interpreting the percent of MB (i.e., MB per total CK) at various time points. The test was reliable in documented early recurrent infarctions that occurred in 3 patients. The method appears to be an attractive alternative to electrophoretic techniques for use in diagnosis of acute myocardial infarction.

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