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Creatine Kinase-MB, CPK-MB

CK MB

CK (creatine kinase) is an enzyme (protein) found in several tissues, including muscles and the heart. Depending on the tissue, different forms of CK are present: CK-MM, primarily present in skeletal muscles, CK-MB with the highest percentage in the heart, and CK-BB, which comes from the brain and smooth muscle, such as the intestinal walls. The specific CK-MB assay is used primarily to diagnose myocardial infarction when total CK levels are high and a troponin assay is not available. CK-MB appears in the blood 3 to 6 hours after the onset of the infarction. It reaches a maximum level in 12 to 24 hours, before returning to normal in 48 to 72 hours. If a second infarction occurs in the interim, the elevated CK-MB level will be prolonged.

A high CK-MB usually reflects a heart muscle injury (infarction, inflammation, trauma, surgery or heart biopsy). Intense muscle exercise can sometimes cause abnormal CK-MB because skeletal muscles contain approximately 7% CK MB. More rarely, kidney failure, chronic muscle disease or hypothyroidism can also increase CK-MB.

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Creatine Kinase MM (CK-MM)

CK (creatine kinase) is an enzyme (protein) found in several tissues, including muscles and the heart. Depending on the tissue, different forms of CK are present: CK-MM is primarily present in skeletal muscles, CK-MB represents 30% of CK from the heart, while CK-BB comes from the brain and smooth muscle, such as the intestinal walls. Atypical forms of CK (macro CK1 and macro CK2) can also be present. CK electrophoresis is most useful when muscular or cardiac disease does not seem to be responsible for the increased level of total CK.