Multicenter reference limits of hs-cTnI and NT-proBNP in a Chinese cohort

OBJECTIVES: This study aimed to validate the analytical performance of high-sensitivity cardiac troponin I (hs-cTnI) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) assays, and to establish age- and sex-specific reference intervals (RIs) using a large multicenter Chinese cohort. METHODS: hs-cTnI and NT-proBNP were measured on a fully automated chemiluminescence platform (Maglumi X8, Snibe, China). Analytical performance was validated following Clinical and Laboratory Standards Institute guidelines. Sex- and age-specific RIs for hs-cTnI (n=2,323) and NT-proBNP (n=2,333) were determined nonparametrically from IFCC-compliant cohorts across six Chinese provinces. RESULTS: Analytical validation confirmed high sensitivity, specificity, satisfactory linearity, and strong interference resistance of hs-cTnI and NT-proBNP. hs-cTnI demonstrated 3.19 % total imprecision near 99th percentile URLs and >99.5 % detectable rates (>LoD) in healthy individuals, meeting third-generation hs-cTn criteria. RIs were established stratified by age and sex. In plasma, RIs of hs-cTnI were 11.97 ng/L for males and 11.61 ng/L for females, while 97.5th percentile URLs of NT-proBNP were 145.00 ng/L overall, 113.63 ng/L for males, and 160.75 ng/L for females. Elevated hs-cTnI levels were observed in residents of Ningxia and in women with central obesity. CONCLUSIONS: The Snibe hs-cTnI assay fulfills IFCC high-sensitivity criteria. Age- and sex-specific RIs of hs-cTnI and NT-proBNP were established from a large multicenter Chinese cohort, confirming their essential role in accurate cardiovascular risk stratification.