Creatine kinase occurs as three isoenzymes based on dimeric combinations of two different polypeptides, i.e. the M (for muscle) and B (for brain) polypeptides. The isoenzymes CK-BB, CK-MB, and CK-MM are found in different proportions in different tissues. CK-BB INCREASES in neurological disease, cancers affecting the digestive tract and after prostatectomy. CK-MB is useful in the diagnosis of myocardial damage; its levels RISE in myopathy, hypothyroidism, polymyositis, and rhabdomyolysis or following intramuscular injection. CK-MM is normally present in patients’ serum.
CPK must be > 100 in order to perform CK Isoenzymes