The quantitation of CK-MB levels in serum is used as an aid in the diagnosis of myocardial injury. Elevated CK-MB levels are associated with myocardial cell death and damage due to acute myocardial infarction (AMI). CK-MB levels can be detected as a result of myocardial injury within 3 to 8 hours following the onset of chest pain with peak concentrations being achieved within 12 to 24 hours and usually returning to baseline levels within 24 to 48 hours.