CK-MB

Background

• Creatine kinase MB isoenzyme; historically used as cardiac biomarker
• Largely replaced by troponin for ACS diagnosis

Normal Values

• Normal: <5 ng/mL (or <5% of total CK)

Interpretation

• Rises 4-6 hours after MI, peaks at 12-24 hours, normalizes in 48-72 hours
• Faster return to normal than troponin makes it useful for detecting reinfarction
• CK-MB:total CK ratio >5% suggests cardiac source
• Largely obsoleted by high-sensitivity troponin for acute MI diagnosis

See Also

• Troponin
• CK
• Cardiac enzymes
• Acute coronary syndrome