Creatine kinase-MB (CK-MB)

What it measures

CK-MB is the isoenzyme of CK found in greatest proportion in heart muscle. It was used to diagnose heart attack and is now mainly used to detect reinfarction or post-procedure injury where troponin remains high.

Specimen and preparation

• Specimen: Serum or lithium-heparin plasma
• Tube: Gold top

Reference range

Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.

Causes of high values

• Myocardial infarction (rises 3–6 h, returns to normal in 48–72 h)
• Myocarditis
• Cardiac surgery or defibrillation
• Severe skeletal muscle injury

Method

Immunoassay (CK-MB mass); older immunoinhibition activity methods

Good to know

Troponin is more sensitive and specific; CK-MB mainly helps time an event because it clears faster.

Related tests