CK-MB
What it measures, and what changes the number.
CK-MB is one of the forms, or isoenzymes, of creatine kinase. It is found in greatest concentration in heart muscle, though skeletal muscle also contains some. The test measures how much of this form is in the blood.
It is usually reported with total CK, and some labs also show CK-MB relative to total CK. It is often read alongside high-sensitivity troponin I, which has largely taken over as the main heart muscle marker, and sometimes with AST.
The assay method changes both the number and the unit. Some labs measure CK-MB mass by immunoassay, while others measure enzyme activity, so results from different methods are not directly comparable. Strenuous exercise and skeletal muscle injury can raise it along with total CK. Labs may print it as Creatina Quinasa MB (CK-MB).
Often read alongside: CK, Troponin I (hs), AST