[Macrocreatine kinase, a cause of MB isoenzyme levels falsely elevated].

The authors describe two cases of falsely elevated CPK-MB levels due to the presence of a Macro-CPK. The quantification of the mass of CPK-MB gave values lower than the cut-off level. Electrophoresis of CPK isoenzymes showed a type 1 Macro-CPK in one case and a type 2 Macro-CPK in the other. The authors recommend electrophoresis of CPK isoenzymes or quantification of mass if the clinical evolution or ECG changes do not correlate with the CPK-MB levels or if there is a low global CPK with high CPK-MB levels.