Decision limit for troponin I on ADVIA:Centaur and evaluation of the analytical precision at low concentrations

Recent guidelines have defined that the decisional cut-off of cardiac troponin (cTn) would recognize "the normal" subjects, and in theory they do not have "measurable" values of cTn. The 99th percentile of this population is chosen as cut-off but using an assay with an analytical CV < 10% at this value. Objectives of this study were to set the decisional limits for cTroponin I (cTnI) measured by the ADVIA:Centaur, and to evaluate the analytical precision around these limits. 120 normal plasma samples were tested for cTnI levels. The 99th percentile defined the decisional level, according to the recent guidelines. The precision was estimated by 10 replicates for 21 samples. The 99th percentile was 0.17 microg/L, with an analytical CV <10%. Since this analytical method achieves the recommended analytical precision, the cTnI decision level for myocardial damage by the ADVIA:Centaur is 0.17 microg/L.