Creatine Kinase (CK) also referred to as creatine phosphokinase (CPK) or phosphocreatine kinase is an enzyme in the body that causes the phosphorylation of creatine. Creatine kinase (CK) is found in the skeletal muscle, cardiac muscle, brain, bladder, stomach and colon. The CPK levels can be elevated by muscle diseases or muscle necrosis. CPK leaks into the blood when a muscles tissue is damaged, and as such high levels of CPK is indicative of stress or injury to the heart or other muscles. The enzyme phosphocreatine kinase has two forms, such as the isoenzymes CKM and CKB, which CPK-MB evaluates in blood levels and comparatively limits. The ratio of CK-MB1 and CK-MB2 isoforms can be measured relatively precisely and easily. The CK-MB test is a blood test that looks for a specific enzyme. That enzyme, creatine kinase-myocardial band, is most common in your heart but can also mean you have damage to other muscles in your body.