ANALYTICAL ASPECTS OF THE AUTOMATED CKMB1,2 AND CKMM1,2,3 ISOFORM DETERMINATION AND ITS RELATION TO OTHER BIOCHEMICAL MARKERS

The automated (CK)MB1,2/MM1,2,3 isoform measurement, based on electrop horesis, has been simplified to the point that it has become possible to perform this analysis on a 24-h routine basis. We studied analytica l aspects of this analysis and its clinical relevance in relation to o ther biochemical markers (CK total, CKMB activity, CKMB mass, myoglobi n, Troponin I and Troponin T) in patients with acute myocardial infarc tion (AMI), patients with unstable angina pectoris (UAP), and healthy donors. Furthermore, the additional significance of the analysis was e valuated in patients with clinically unexpected, raised CKMB/CK total activities. The storage of serum at 4 degrees C does not influence the MB2/MB1 ratios, whereas storage at 20 degrees C changes them signific antly. MM3/MM1 and normal MB2/MB1 ratios show lower coefficients of va riation than increased MB2/MB1 ratios. Between 2 and 30 h after myocar dial tissue damage, AMI patients showed a characteristic change in CK isoform patterns. At a mean time of 3.6 h after the onset of symptoms we found raised MB2/MB1 ratios in 94% of these patients. With the info rmation of the CK isoform analysis unexpected abnormal CK activities c ould be explained by CK macro enzymes (Ig-bound and mitochondrial), in sufficient CE; clearance capacity, enzyme activities 4 h after (re-)in farction, and raised CK activity 15 h after skeletal muscle damage. We conclude that the CK isoforms are relatively simply to assess; they a re adequate tools with which to indicate the CK kinetics over a period lasting between 2 and 30 h after tissue damage with a single blood sa mple and a single analysis; the CK isoform analysis has additional val ue in explaining inappropriate CKMB/CK total activities, and the MB2/M B1 ratios show to be one of the best early parameters for discriminati ng patients with AMI on admission to hospital.