Sensitivity and specificity of MB creatine kinase activity determined with column chromatography

Abstract

Several analytic techniques are used to estimate the activity of creatine kinase (CK) isoenzymes. These techniques are undergoing continual refinement because the MB CK molecule appears to be nearly cardiospecific. An improved column chromatographic assay is presented with a lower limit of analytic detection of 0.8 mlU/ml. The assay was applied to normal subjects and to patients with myocardial infarction and with complex disease states. Results of the column chromatography were compared with those of agarose and cellulose acetate electrophoresis. There was MB CK activity in all normal sera (no. = 19, mean +/- standard deviation = 2.4 +/- 7). After acute myocardial infarction the MB CK activity increased by 650 percent (no. = 86, mean +/- standard error of the mean = 158.2 +/- 12.6 mlU/ml). The sensitivity for myocardial infarction was 100 percent. The specificity, evaluated in multiple clinical states, approached 100 percent. The column assay was compared with both agarose and cellulose acetate electrophoresis, and poor correlations with these semiquantitative systems were demonstrated. Finally, peak MB CK activity was closely correlated with kinetic analyses used to estimate infarct size (r = 0.94). Thus, column chromatography is a sensitive and specific method of estimating MB creatine kinase activity and is more precise than current electrophoretic methods.