The identification of AKI biomarkers in different scenarios has been extensively investigated in the literature to predict acute tubular necrosis, worsening of renal function during hospitalization, and estimated glomerular filtration rate at 6 months, including urinary NGAL (neutrophil gelatinase-associated lipocalin), CXCL9, TNF-α, IL-9, KIM-1 (kidney-injury molecule-1), NAG (N-acetyl-β-D-glucosaminidase), uromodulin, osteopontin, and YKL-4054. This evidence concerns the gene IL9 and acute kidney injury.