Analytical evaluation of two automatic methods to measure blood CK-MB mass and troponin I

The lack of standardization of methods to measure cardiac markers for coronaria ischaemia, particularly troponin, led us to perform an analytical evaluation of two new immunoassays to quantify CK-MB mass and troponin I using the Dimension R×L automatic analyser. The reliability and analytical intervals of the methods were studied as well as reference values (0.010— 0.228 μg l(-1) for troponin I, 0.20—3.90 mg μg l(-1) for CK-MB mass) and cuto¡ values (0.77 μg l(-1) for troponin I, 5 μg l(-1) for CK-MB mass) established. The cutoff values were established from 37 patients with acute myocardial infarction and from 20 with unstable angina. The absence of method cross-reactivity was corroborated using myocardial, brain and skeletal muscle tissue. Both methods were highly specific and showed good reliability and practicability in the diagnosis of coronaria ischaemia after 6 h of precordial pain.