The reference intervals of PT, INR and APTT tests on the Cobas analyzer in Turkish pediatric population

The aim of this study was to establish reference intervals (RIs) for prothrombin time (PT), international normalized ratio (INR) and activated partial thromboplastin time (APTT) in the Turkish pediatric population using the Cobas t511 analyzer. This retrospective study included preoperative laboratory results from 1065 healthy pediatric patients (aged 0-18 years) who underwent minor elective surgeries. RIs were established following Clinical and Laboratory Standards Institute (CLSI) guidelines and were summarized as 2.5th-97.5th percentile reference limits using nonparametric approach. The overall median (95% RI) values were 9.0 s [8.1-10.5] for PT, 1.02 [0.93-1.17] for INR, and 29.7 s [24.3-35.2] for APTT. Statistically significant differences were observed in PT, INR and APTT across age groups (<i>p</i> < 0.001). Accordingly, data were stratified into 18 age partitions, and reported for each group. In conclusion, our study provides pediatric-specific RIs for PT, INR and APTT using the Cobas t511 analyzer in a Turkish cohort. These age-stratified intervals can improve the interpretation of coagulation tests in clinical practice and contribute to more accurate pediatric diagnostics.