Creatine Kinase (CK) Isoenzymes with Total CK

Creatine kinase is an enzyme concentrated in skeletal muscle and heart, and a rising level signals muscle damage or breakdown. This test reports total CK plus its three isoenzyme fractions: CK-MM (skeletal muscle and heart), CK-MB (mainly heart), and CK-BB (brain and smooth muscle), separated by electrophoresis. The fractionation matters because total CK alone tells you damage is happening but not where it originates. Elevated CK shows up in inflammatory myopathies, muscular dystrophy, rhabdomyolysis, hypothyroidism, statin-related muscle injury, and after trauma or hard exercise, and in neuromuscular disorders a raised CK can be the only early sign. For diagnosing a heart attack, troponin has replaced CK-MB and is more cardiac-specific, so this panel is most useful for muscle questions rather than acute cardiac ones.

The sibling tests narrow the scope: the isoenzyme panel without total CK reports only the fractions, the total CK test gives the single overall number, and the CK-MB mass and activity tests isolate the cardiac fraction. This combined panel is the right default when you want both the total and the tissue breakdown in one draw.