Measurement of creatine kinase MM sub-type by anion-exchange liquid chromatography

Electrophoretic and isoelectric focusing studies have demonstrated the presence of multiple sub-forms of the major creatine kinase isoenzymes, and preliminary work has suggested that measurement of the mm sub-forms provides early diagnostic information concerning acute myocardial infarction. We developed an isocratic method based on liquid chromatography to examine further the clinical potential of measuring these sub-forms. An anion-exchange column is used coupled with the fluorometric detection of NADPH after reaction of the sub-forms with CK reagents, which are added through a post-column pump. We examined various chromatographic variables in producing the best separations. Results for blood collected from normal individuals and patients with acute myocardial infarction and skeletal muscle diseases are compared. We conclude that for routine CK-MM sub-form analysis, this chromatographic procedure is better suited than isoelectric focusing because of the faster turn-around and lower costs.