Creatine kinase isoenzyme band mimicking CK MB on agarose gel electrophoresis

The authors report the case of an 80-year-old man with prostatic disease whose serum contained an aberrant band in the MB position on agarose gel electrophoresis of creatine kinase (CK) isoenzymes. The authors demonstrated that the band probably was CK BB; the patient had no evidence of myocardial infarction. Contrary to most previous reports of such cases, the aberrant enzyme did not appear to be linked with IgG, IgA, or IgM; it also did not behave as if attached to a chelatable cation. Care must be taken to avoid mistaking such bands for CK MB.