Repeat measurements on patient samples identifies unpredictable and poorly reproducible cardiac troponin results with a high-sensitivity cardiac troponin assay
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There is much current interest in the use of low-normal high-sensitivity cardiac troponin (hsTn) concentrations, with or without minimal change, to rule out myocardial infarction (MI). Clifford-Mobleyâs observations demonstrate that this a challenge even for platforms measuring hsTnT.1 Analytical imprecision may also affect algorithms that use hsTn change alone to rule in MI. For example, the imprecision observed with the Ortho hsTnI assay (Ortho Clinical Diagnostics, New Jersey, United States), using quality control or patient pools, has been found to exceed the European Society of Cardiology 0/1h algorithm criterion.2 The Ortho hsTnI assay has also been shown to yield high and non-reproducible results (i.e., outliers), in addition to the problems with imprecision.3 Outliers are often identified by repeat centrifugation and repeat testing. However, Ortho hsTnI results above the 99th percentile cutoffs may be discordant with respect to other cardiac troponin assays and the clinical diagnosis, even when imprecision from duplicate analysis is acceptable.4 As part of a stability study assessing Ortho hsTnI concentrations in both EDTA plasma and lithium heparin plasma over 24h, we have observed that this interference is random and not related to time on cells.
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