The goal of this study is to create a new prognostic score based on changes in serial laboratory data from pediatric acute liver failure patients (PALF). Researchers analyzed data from 146 children with PALF at Seoul National University Children’s Hospital (SNUCH) and Asan Medical Center (AMC). For up to 7 days after PALF diagnosis, daily morning laboratory records were obtained: total bilirubin (TB), the international normalized ratio for prothrombin time (INR) at enrolment; peak TB, peak INR, peak ammonia; the difference between the peak TB and TB at enrollment, the difference between the peak INR and INR at enrollment, the maximum change in serial TB, the maximum change in serial INR level. Nontransplanted patients in SNUCH and AMC were allocated to derivation and validation cohorts, respectively. The nonsurvival group had substantially higher peak TB, daily TB, peak INR, and daily INR. They created a new measure that can predict death in people who have not had a transplant. In the derivation cohort, the AUC was 0.918, and in the validation cohort, it was 0.947. A prognostic grading system based on the change in TB/INR may be effective in predicting death in PALF patients.