Creatine Kinase Isoenzymes (CK Isoenzymes) without Total CK

Creatine kinase is an enzyme that leaks into the blood when muscle tissue is damaged, and it exists in three forms: CK-MM (skeletal and cardiac muscle), CK-MB (mainly heart, with a small amount in skeletal muscle), and CK-BB (brain and smooth muscle). This test reports each fraction as a percentage of total CK, which helps localize the source of an elevated CK rather than just confirming that one exists. A high CK-MM fraction points to skeletal muscle causes such as inflammatory myopathy, muscular dystrophy, rhabdomyolysis, intense exercise, hypothyroidism, or statin and fibrate effects, while chronic muscle disease or chronic kidney failure can raise CK-MB through fetal reversion. CK-MB once dominated heart-attack workups but has been replaced by troponin, which is more cardiac-specific, so this fractionation is now mainly used to characterize muscle disorders.

This version reports the isoenzyme percentages only. If you also want the total CK enzyme activity in the same order, the "Creatine Kinase Isoenzymes with Total CK" version adds that measurement, which is what makes the fraction percentages most interpretable.