In adults, the elevation of cardiac troponin (cTn) above the 99th percentile upper reference limit defines myocardial injury. The use and interpretation of cTn in a paediatric population, however, is difficult given the 99th percentile for different assays is not well established. Using paediatric blood samples from healthy neonates, infants and children we derived continuous and partitioned 97.5th and 99th percentiles for the Ortho VITROS hs-TnI assay.
A total of 328 samples for infants, children and adolescents aged 0–17.8 years were obtained. Age partitioned reference limits were derived in accordance with CLSI EP28-A3C. Continuous reference limits were established as described previously by the HAPPI Kids Study team.
hs-TnI as measured by the Ortho VITROS Assay is highly elevated above the adult 99th percentile at birth and declines to lower levels within the first 6 months of life. The 99th centile upper reference limit for ages 0–3 months was 72 ng/L (90% CI: 52–91) and 9 ng/L (90% CI: 5.2–17.4) for ages 3 months to 18 years. Continuous upper 99th centile reference limits were comparable.
Partitioned and continuous 99th percentiles for hs-TnI were derived for the new Ortho VITROS assay in healthy neonates and older children. This will assist clinicians to appropriately assess for the presence of myocardial injury in this population.
The authors thank staff of the Pathology Collection, Anaesthetic, Surgical, and Neonatal and Post-Natal Departments at the Royal Children’s Hospital, Royal Women’s Hospital, Northern Hospital, and Western Health–Sunshine Hospital, Melbourne. The authors also acknowledge the contribution of scientists and clinical biochemists at The Royal Children’s Hospital.
Research funding: This study was funded by The Royal Children’s Hospital Foundation, with supplementary funding from Ortho Clinical Diagnostics.
Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.
Competing interests: Authors state no conflict of interest.
Informed consent: Informed consent was obtained from all individuals included in this study.
Ethical approval: The study protocol was approved by The Royal Children’s Hospital, Melbourne, Australia Ethics in Human Research Committee (HREC) (HREC 34183 A).
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