TF2 employed the Renal Angina Index (RAI) (RAI +  ≥ 8) and urine neutrophil gelatinase-associated lipocalin (uNGAL; uNGAL +  ≥ 150 ng/mL) to aid in the risk prediction of severe AKI (sAKI; ≥ KDIGO stage 2) at PICU day 2-4. Here, LCN2 is linked to acute kidney injury.