Establishment of Age‐Specific Reference Intervals for 16 Coagulation Parameters in Chinese Children Using Sysmex CN‐6000 Analyzer: A Cross‐Sectional Study

ABSTRACT Background and Aims Children's coagulation system undergoes dynamic changes during development, necessitating age‐specific reference intervals (RIs). This study aimed to establish RIs for 16 coagulation parameters in Chinese children aged 0–18 years using the Sysmex CN‐6000 analyzer. Methods We conducted a cross‐sectional study in children aged 0 day to 18 years who met the inclusion and exclusion criteria. Participants were stratified into six age groups (0–30 days, 1–6 months, 6–12 months, 1–3 years, 3–12 years, and 12–18 years) and blood samples were collected. Routine parameters (APTT, PT, PT‐INR, TT, Fibrinogen [Fib]), thrombotic markers (AT‐III, D‐Dimer [D‐Di], Fibrin Degradation Products [FDP]), and coagulation factors (II, V, VII, VIII, IX, X, XI, XII) were analyzed using the Sysmex CN‐6000 analyzer. RIs and their 90% confidence intervals (CIs) were calculated using the non‐parametric method (for n ≥ 120) or the robust method (for n < 120). Results Neonates exhibited distinct coagulation profiles, including prolonged APTT (22.7 s–46.5 s) and TT (16.2 s–20.8 s), reduced levels of anticoagulant and coagulation factors (e.g., AT‐III: 23.1%–91.3%, factor II: 26.5%–77.5%), and elevated fibrinolytic markers (D‐Di ≤ 1.41 μg/mL; FDP ≤ 4.44 μg/mL). Age‐dependent trends were evident: APTT shortened until adolescence (24.7 s–32.9 s), while factor IX increased progressively (16.3% – 43.2% in neonates vs. 43.6%–108.6% in adolescents). Novel RIs for neonatal D‐Di and FDP were established, addressing a critical gap in developmental hemostasis. Sex‐specific differences in TT were observed but deemed clinically insignificant. Conclusion Age‐specific RIs are essential for children. This study provides the first comprehensive RIs for Sysmex CN‐6000 in Chinese children, aiding in the diagnosis and management of coagulation disorders in pediatrics.