Tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7) are preformed molecules that are released into the urine within minutes of injury.6 Similarly, neutrophil gelatinase-associated lipocalin (NGAL) is upregulated and observed in the urine at 2 hours, 36 hours before changes in SCr for patients with AKI.7 This evidence concerns the gene LCN2 and acute kidney injury.