Increased creatine kinase MB in the absence of acute myocardial infarction.

Although measurement of CK-MB is a very sensitive, specific, and cost-effective test for use in diagnosis or exclusion of acute myocardial infarction, it should not be used as the sole diagnostic indicator, and all positive values must be critically analyzed to exclude other causes of increased values in serum. This is particularly important when the population being tested consists of patients with multiple medical problems, with low to medium probability of myocardial infarction, and without clinical or other biochemical (i.e., LDH 1) evidence of acute myocardial infarction. When the temporal pattern and absolute CK-MB values are considered together with the patient's clinical status, the diagnostic specificity is dramatically increased. In addition, one must be familiar with the limitations of individual assay systems in order to exclude method-related artifactual values.