Verification and Establishment of Reference Intervals for Prothrombin Time and Activated Partial Thromboplastin Time for Children in a Clinical Laboratory

BACKGROUND: Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are routine coagulation tests. The absence of age-dependent reference interval (RI) may lead to abnormal results in children. In this study, we aimed to verify adult-based RIs in children and establish pediatric RIs for PT and aPTT. METHODS: We analyzed PT and aPTT results. Samples from inpatients and outpatients aged 1 - 18 years, considered healthy subjects, were divided into six groups by age. Verification and establishment of RIs were conducted. RESULTS: Applying adult-based RIs to pediatrics was statistically invalid for individuals aged 10 - 18 years for PT and invalid throughout childhood for aPTT. The new RI of PT for individuals aged 10 - 18 years was 11.1 - 14.1 seconds and that of aPTT for individuals aged 1 - 9 years was 28.2 - 46.0 seconds. CONCLUSIONS: Pediatric RIs were higher than adult-based RIs. Using pediatric RI can save time, labor, and costs to make clinical decision.