Not medically reviewed
Cardiac
Creatine kinase MB isoenzyme (CK-MB mass)
Not medically reviewed · Content last updated · 1 min read ·
This is the date the draft was written, not a medical review date.
The cardiac-enriched isoenzyme of creatine kinase. It has largely been replaced by troponin for diagnosing myocardial infarction, but can still be used to detect re-infarction because it returns to baseline within 48 to 72 hours.
Reference interval
| Conventional (ng/mL) | SI (µg/L) | |
|---|---|---|
| Adults | < 5 (upper limit) ng/mL | < 5 (upper limit) µg/L |
Specimen: Serum or heparinised plasma · Conventional × 1 = SI
Causes of high values
Myocardial infarction, myocarditis, cardiac surgery and defibrillation, skeletal muscle injury (rhabdomyolysis, intense exercise, myopathies), chronic renal failure, macro-CK.
Causes of low values
Not clinically significant.
Pre-analytical and method notes
Mass assays (ng/mL) and activity assays (U/L) are not interchangeable, and a relative index (CK-MB divided by total CK) is used by some laboratories to help exclude a skeletal muscle source. Troponin is now preferred for diagnosis under current universal definitions. Reference intervals vary by laboratory, method and population; use the interval printed on the report.
References
- Fourth Universal Definition of Myocardial Infarction (2018). ESC / ACC / AHA / World Heart Federation (2018) — Tier 2 (guidelines / primary literature)
- Rifai N, Horvath AR, Wittwer CT. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Elsevier, 6th edition (2018) — Tier 3 (textbook)
- McPherson RA, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. Elsevier — Tier 3 (textbook)
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