CK-MB (synonyms: creatine kinase isoenzyme MB, creatine kinase myocardial type) is found primarily in the myocardium (heart muscle). It accounts for about six percent of creatine kinase.

CK-MB is used primarily in myocardial infarction diagnostics.

An increase in CK-MB can be expected after 3 to 12 hours after the onset of infarction. The maximum is between 12 and 24 hours after infarct onset. CK-MB usually returns to normal after 2 to 3 days.

The procedure

Material needed

  • Blood serum; centrifuged to avoid hemolysis during prolonged sample transport.

Preparation of the patient

  • Not known

Disruptive factors

  • Dark-skinned individuals have higher levels (increased up to 1.5 times)
  • Weight-loss preparations containing cheyenne pepper, bitter orange, and amphetamines may damage the myocardium and increase CK-MB levels via sympathetic activation.
  • Avoid hemolysis. Adenylate kinase from erythrocytes (red blood cells) increases enzymatically measured CK and CK-MB.

Normal values

Normal value in U/l (new reference range; measurement at 37 °C). 0-25
Normal value in U/l (old reference range; measurement at 25 °C). 0-10


  • Suspected myocardial infarction (heart attack) for early diagnosis and follow-up:
    • Suitable for rough estimation of infarct size.
    • Reveals reinfarction more reliably than TnT because CK-MB normalizes faster (after 2- 3 days) than TnT (after up to 10 days)


Interpretation of increased values

  • Myocardial infarction (heart attack)

Interpretation of decreased values

  • Not relevant to the disease

Further notes

  • If myocardial infarction is suspected, the following laboratory parameters should be determined:
    • Myoglobin
    • Troponin T (TnT)
    • CK-MB (creatine kinase myocardial type).
    • CK (creatine kinase)
    • Aspartate aminotransferase (AST, GOT)
    • LDH (lactate dehydrogenase)
    • HBDH (hydroxybutyrate dehydrogenase)