Creatine kinase is an enzyme consisting of three major isoenzymes, CK-BB (brain), CK-MB (heart), and CK-MM (skeletal muscle). CK-BB is rarely present. It has been described as a marker for adenocarcinoma of the prostate, breast, ovary, colon, and GI tract, and for small cell anaplastic carcinoma of the lung. CK-BB has been reported with severe shock and/or hypothermia, infarction of bowel, brain injury, stroke, as a genetic marker in some families with malignant pyrexia, and with MB in alcoholic myopathy. CK-MM is found in normal serum.
Use
Detection of macroforms of creatine kinase (CK)
Diagnosing skeletal muscle disease, in conjunction with aldolase
CK isoenzymes are not widely used in clinical practice today due to the use of troponin and CK-MB mass assays but may be useful in differential diagnosis when CK elevated as well
The CK-BB isozyme is rarely encountered clinically.
Interpretation
Increased In
Malignant hyperthermia, uremia, brain infarction or anoxia, Reyes syndrome, necrosis of the intestine, various metastatic neoplasms (especially prostate), biliary atresia