Five creatine kinase isoenzymes in serum of a patient with severe heart disease.

Abnormal creatine kinase (CK) isoenzyme patterns were observed in the serum of a 64-year-old woman with severe heart disease. Agarose electrophoresis revealed the presence of all the usual CK isoenzymes (MM, MB, and BB) plus an extra band between MM and MB. Total serum CK activity was within the normal range. Within 2 h after the patient suffered cardiorespiratory arrest, a fifth CK isoenzyme appeared, cathodal to MM. After cardiac valve replacement, the patient's serum showed a high activity of CK, but the isoenzyme pattern showed only MM and, transiently, an MB band. With return of the serum CK activity to normal, the CK isoenzymes pattern also became normal, virtually ruling out genetic variant(s). The abnormal CK isoenzyme patterns might have been the consequence of severe hypoxemia in the patient, thus such patients may represent an ominous prognostic sign. The association of the abnormal pattern upon admission with rapid deterioration of the condition of the patient suggests prompt attention for the prevention of complications.