title: Macro creatine kinase type 1 with electrophoretic mobility identical to that of the MB isoenzyme.
abstract: We describe the case of an elderly woman whose symptoms and electrocardiographic pattern initially suggested acute myocardial infarction. The value for total serum creatine kinase (EC 2.7.3.2; CK) was 737 U/L (reference interval: 22-269 U/L), and electrophoresis for CK isoenzymes demonstrated two bands, the more anodal migrating to the CK-MB region and the second migrating between the CK-MB and CK-MM regions. The above-normal total CK and electrophoretic pattern persisted during her 11-day hospital course. The QuiCK-MB (International Immunoassay Labs.) and Tandem-E CK-MB (Hybritech) immunoassays, however, showed CK-MB mass measurements within the normal range. In further investigation with a mixture of patient's serum and human-serum-based control containing all CK isoenzymes, the electrophoretic mobility of only CK-BB was altered, proving that the patient had antibody to the B unit of CK in her serum. Immunofixation revealed the more anodal band to be a CK-IgA lambda complex, and the more cathodal band, a CK-IgG kappa complex. Mixing the patient's serum with polyclonal antibody specific for CK-B slowed the electrophoretic mobility of only the more anodal band. Polyclonal antibody specific for CK-M had no effect on either band. Evidently, this patient had two different types of macro CK type 1, both containing CK-BB. We conclude that macro CK type 1 can mimic CK-MB and be a source of confusion.
mesh_terms: D000368:Aged; D003402:Creatine Kinase / Q000097:blood*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000201:enzymology; D004587:Electrophoresis, Agar Gel; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000201:enzymology; D007163:Immunosorbent Techniques; D007527:Isoenzymes; D009203:Myocardial Infarction / Q000150:complications / Q000201:enzymology
chemical_list: D007527:Isoenzymes; D003402:Creatine Kinase