Test Details: Creatine phosphokinase (CPK or CK) is an enzyme found in the heart, brain and skeletal muscles. When the muscle tissue is damaged, CPK leaks into the blood. High levels of CPK indicate injury to heart or other muscle. This test is also done for diagnosing and or monitoring myopathies or other trauma, toxin, or drug-induced muscle injury, muscular dystrophy, brain injury.