Test Details: CK-MB is an Isoenzyme of creatinine kinase. It is a cardiac marker used to aid in the diagnosis of acute myocardial infection, myocardial ischemia, myocarditis. CK-MB is cardiac specific and hence is most likely ordered if a person has chest pain, extreme fatigue, nausea. CK-MB is done at times to distinguish between skeletal muscle and myocardial damage.