Cathodic isozyme of serum creatine kinase in a case of stomach cancer complicated by disseminated intravascular coagulation.

A rare isozyme of serum creatine kinase (CK) migrating cathodic to CK-MM on electrophoresis was found in a 30-year-old male with stomach cancer complicated by disseminated intravascular coagulation leading to massive upper gastrointestinal bleeding and marked anemia. Serum CK activity rose to a maximum of 374 U/l without detectable CK-MB isoenzyme. The patient was also characterized by a marked increase in serum lactate dehydrogenase (all isozymes elevated) and by preferential leakage of mitochondrial aspartate aminotransferase and glutamate dehydrogenase, indicating the presence of extensive tissue damage involving mitochondria. Skeletal muscle mitochondria were considered the most likely source of the additional CK isozyme.