Jaffe, A. S.

Abstract Background The clinical use and interpretation of cardiac troponins (cTn) in pediatric patients is heterogeneous. Content This review is based on an appraisal and synthesis of the available literature and discussions between International Federation of Clinical Chemistry and Laboratory Medicine Committee on Clinical Application of Cardiac Biomarkers members and pediatricians, cardiologists, emergency department physicians, and laboratorians. It aims to summarize current knowledge and best practices related to cTn measurements in pediatric patients, including which percentile should be applicable as the upper reference limit, and the influence of age, sex, and physiology on circulating concentrations. Preanalytical and analytical precautions, and a consensus on optimal interpretation of the reported results are discussed. Summary Current studies report high cTn concentrations in healthy infants and newborns. The nadir is reached at 1–3 years at which time concentrations gradually increase, reaching adult levels through puberty. The incidence of myocardial injury is reported to be low and dependent on whether the 97.5th or 99th percentile is chosen as the upper reference limit. The main clinical indication for testing appears to be suspicion of myo/pericarditis or traumatic chest injury. On occasion, cTn is measured in cases of possible heart failure and/or myocardial ischemia. There is heterogeneity among the limited clinical studies published. Most of the data are retrospective, and the current suggestions for clinical practice are thus largely based on expert opinion. More research is needed regarding all aspects of cTn testing in children, and suggestions for future research are included at the end of this review.

Abstract Background High-sensitivity cardiac troponin (hs-cTn) assays are recommended for the diagnosis of acute myocardial infarction. Here, we characterize the analytical performance of a next-generation hs-cTn assay, Elecsys® Troponin T hs Gen 6 (Roche Diagnostics International). Methods Surplus lithium-heparin plasma or serum samples from patients or healthy volunteers were run on Cobas® e 801, e 402, and Pro analyzers. Limits of blank (LoB), limits of detection (LoD), and limits of quantitation (LoQ) were determined according to CLSI EP17-A2, with target values of 1.0 and 1.5 ng/L for LoB/LoD and 3.0 ng/L (10% CV) and 1.5 ng/L (20% CV) for LoQ, respectively. Precision was measured, per CLSI EP17-A2, using 3 QC samples (approximately 4, 30, and 220 ng/L), 12 native samples, and 3 reagent lots. Linearity, per CLSI EP06-Ed2, was determined by diluting samples with cardiac troponin T (cTnT) concentration above the measuring range with a low/blank sample. Interference (per Glick) with endogenous and assay components at 5 cTnT concentrations was assessed. Results Measured values for LoB, LoD, and LoQ at 10% and 20% CV were 0.1 to 0.7 ng/L, 0.3 to 1.4 ng/L, 1.0 to 2.9 ng/L, and 0.4 to 1.2 ng/L, respectively. Repeatability CVs were 1.0 to 5.8% for mean cTnT concentrations of 2.6 to 9230 ng/L in lithium-heparin plasma. High precision was shown across lots, and linearity was observed across the measuring range (1.5 to 9500 ng/L, all Pearson's r = 1.00). No interferences were observed, specified up to ≤1000 mg/dL hemoglobin, ≤50 mg/dL [≤855 µmol/L] icterus/bilirubin, and ≤1200 ng/mL biotin. Conclusions The analytical performance characterization of the assay demonstrated high sensitivity, high precision at the low end and across the measuring range, and resistance to interference.