CKMB

Keywords: CK isoenzyme MB, Creatine kinase MB isoenzyme, Creatine kinase isoenzymes

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This test has been superseded by cardiac Troponin T or Troponin I for the diagnosis of Myocardial infarction.

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 percentage 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.