Comprehensive Pediatric Reference Limits for High-Sensitivity Cardiac Troponin I and NT-proBNP in the CALIPER Cohort

Background: Cardiac biomarkers have increasing application in pediatric populations, including congenital heart disease, myocarditis, and heart failure. Clinical practice is limited by evidence gaps in pediatric reference limits to inform clinical decision-making. The current study aimed to establish comprehensive pediatric reference limits for N-terminal (NT)-pro hormone brain natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin I (hs-cTnI) in the CALIPER cohort of healthy children and adolescents. Methods: Analytical immunoassay performance was assessed through precision, linearity, and method comparison (Abbott Alinity ci system). Subsequently, approximately 200 serum samples collected from apparently healthy children (birth to 18 years) were analyzed for hs-cTnI and NT-proBNP. Reference limits (2.5th, 97.5th, and 99th percentiles) were established as per Clinical and Laboratory Standards Institute EP-28A3c guidelines with associated 90% confidence intervals. Results: Of all pediatric serum samples analyzed, 46% had detectable hs-cTnI concentrations (limit of detection: 1.3 ng/L). Both hs-cTnI and NT-proBNP demonstrated markedly elevated neonatal concentrations with 99th percentiles of 55.8 and 1785 ng/L, respectively. No statistically significant age-specific differences were observed beyond 1 year of age across all cardiac biomarkers examined. No sex-specific association was observed between hs-cTnI and NT-proBNP concentration and adolescence. Conclusions: We report age-specific reference limits for hs-cTnI and NT-proBNP in a healthy Canadian cohort of children and adolescents measured using Alinity immunoassays for the first time. These data support the need for pediatric-specific interpretation to reduce misinformed clinical decision-making and calls to action larger cohort studies such that reference limits can be more robustly defined.