Creatine kinase MB isoenzyme - plasma or serum
Last updated: Wednesday, 14, April, 2004
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| Item | Process |
|---|---|
| Specimen | 5 mL blood in lithium heparin or plain tube. |
| Method | Immunoassay, electrophoresis, spectrophotometry. |
| Reference Interval | 0-10 U/L; 0-5% of the total CK (enzyme activity) 0-6 mg/L (immunoassay). |
| Application | This test has been superseded by cardiac troponin T or I for the diagnosis of myocardial infarction. May be useful for confirming reinfarction. |
| Interpretation | CKMB elevation takes about four hours to develop after myocardial infarction, and levels usually return to normal within 48 hours. Elevation of total CK, and CKMB as a percentage of CK, indicates a myocardial origin of CK. If the total CK is <100 U/L, elevation of CKMB (as a percent of CK) is unreliable as an indicator of myocardial infarction. There is <5% CKMB in skeletal muscle, so although skeletal muscle disease or damage may cause an increase in total CKMB, the level will be <5% of total CK. |
| Reference | Adams JE et al. Clin Chem 1994; 40(1): 1291-1295. |