CPK Isoenzymes
Alternate Names : CK - Isoenzymes, Creatine Kinase - Isoenzymes, Creatine Phosphokinase - Isoenzymes
DefinitionThis blood test measures the isoenzymes (different forms) of creatine phosphokinase.
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Why is the Test Performed?
CPK isoenzymes are performed when the total CPK level is elevated. Isoenzyme testing can help differentiate the source of the damaged tissue.
CPK is an enzyme found predominantly in the heart, brain, and skeletal muscle. CPK is composed of 3 isoenzymes that differ slightly in structure:
- CPK-1 (also called CPK-BB) is concentrated in the brain and lungs
- CPK-2 (also called CPK-MB) is found mostly in the heart
- CPK-3 (also called CPK-MM) is found mostly in skeletal muscle
Because the CPK-1 isoenzyme is predominately found in the brain and lungs, injury to either of these organs (for example, stroke or lung injury due to a pulmonary embolism) are associated with elevated levels of this isoenzyme.
CPK-2 levels rise 3 to 6 hours after a heart attack. If there is no further damage to the heart muscle, the level peaks at 12 to 24 hours and returns to normal 12 to 48 hours after tissue death. CPK-2 levels do not usually rise with chest pain caused by angina, pulmonary embolism (blood clot in the lung), or congestive heart failure.
The CPK-3 isoenzyme is normally responsible for almost all CPK enzyme activity in healthy people. When this particular isoenzyme is elevated, it usually indicates injury or stress to skeletal muscle.
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