Aims & Objectives: Acute kidney injury (AKI) affecting up to 30% of children admitted to pediatric intensive care unit (PICU). While creatinine serves as the primary marker for AKI, its effectiveness in early diagnosis is limited. The renal angina index (RAI) has emerged as a promising predictive model for early AKI detection, yet its performance in Colombia remains largely unexplored. This study aimed to evaluate the diagnostic efficacy of a positive RAI in predicting severe AKI in critically ill children Methods: A prospective, analytical, multicenter diagnostic test study was conducted from August 2022 to February 2023, involving patients aged 1 month to <18 years across three PICUs. Creatinine levels were measured at baseline and 72 hours post-admission, with RAI positivity defined as ≥8. AKI development was assessed using the KDIGO classification, with outcomes monitored up to day 28. Results: Analysis of 191 patients revealed an AKI incidence of 12.5/100, with 26% exhibiting a positive RAI and 12.6% developing severe AKI at 72 hours. When comparing with negative, 75% RAI-positive patients experienced severe AKI (RR 3.23; 95% CI 1.61-6.49), 14% required renal support therapy (RR 2.09; 95% CI 0.95-4.59), and 8% died within 28 days (p=0.964). The sensitivity of RAI for early diagnosis of severe AKI was 85.71%, specificity 78.3%, PPV 24%, NPV 98.5%, AUC 0.812 (95% CI 0.72-0.92) Conclusions: RAI emerged as a valuable marker for early severe AKI prediction in critically ill children, potentially enhancing outcomes compared to sole reliance on creatinine assessment Keywords: Acute kidney injury, Critical care, child, creatinine