Creatine Kinase MB (CK-MB)

What is a Creatine Phosphokinase -MB (CKMB/CPKMB) test? Creatine kinase-MB (CK-MB) is a form of an enzyme that is found primarily in the heart muscles. This test measures the CK-MB in the blood. The CK-MB is one of three forms (isoenzymes) of the enzyme in creatine kinase (CK). These isoenzymes include CK-MM (found in skeletal muscles and the heart), CK-MB (found mostly in the heart, but small amounts are found in skeletal muscles), and CK-BB (mostly found in the brain and smooth muscles, such as the intestines and uterus).