• Cardiac Troponin T is a more sensitive and more specific marker of cardiac damage than CKMB. Troponin has largely replaced CKMB
• Total CK is always assayed first. CKMB is not generally performed where Total CK is < 200 U/L, and is not indicated where Total CK is > 10,000 U/L
• The CKMB (mass) assay is largely free from the non-specific reactions seen in the older enzyme-activity assays
• Caution should be exercised in the diagnosis of myocardial damage where the total CK is very high, eg: > 5000 U/L.
• Small amounts of CKMB may be found in skeletal muscle
• Both percent and absolute levels of CKMB may exceed the quoted values

Myocardial damage is probable when the following triad exists: