Creatine Kinase MB Fraction (CK-MB), Serum/Plasma


The hybrid MB isoenzyme is detected almost exclusively in the myocardium. Normally, CK-MB cannot be detected in the serum. It may be released from skeletal muscle in such disorders as progressive muscular dystrophy, dermatomyositis, or conditions associated with myoglobinuria, but these conditions can be clinically recognised.


The importance of CK-MB for the diagnosis of acute myocardial infarction (AMI) rests chiefly upon its specificity for myocardial damage. Nonetheless, in a subgroup of patients the detection of serum CPK-MB is not associated with AMI but with myocardial necrosis secondary to cardiac trauma. The myocardial-specificity of CK-MB is even more valuable as a marker for AMI after cardiac surgery when other criteria for AMI have many limitations. CK-MB is present in the serum for periods of 24-72 hours after an initial appearance at 2-12 hours after the onset of symptoms of AMI.

Sample Type, Quantity & Conditions

1 ml Serum 1 ml Li-Heparin Plasma Stability in Serum: 8 Hours at 20-24 °C 8 Days at 2-8 °C 4 Weeks at -20 °C Stability in Li-Heparin Plasma: 8 Hours at 20-24 °C 5 Days at 2-8 °C 8 Days at -20 °C

Special Precautions

Avoid haemolysis.

Normal Range

Up to 25 U/L Up to 0.421 µkat/L

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