Lipocalin-2, also known as neutrophil gelatinase-associated lipocalin (NGAL) or oncogene 24p3, is expressed in neutrophils and in low levels in the kidney, prostate, and epithelia of the respiratory and alimentary tracts. Lipocalin-2 is involved in innate immunity by sequestrating iron that in turn limits bacterial growth. It is used as a biomarker of kidney injury. In the case of acute kidney injury (AKI), Lipocalin-2 is secreted in high levels into the blood and urine within 2 hours of injury. The Lipocalin-2 level measured in an individual is proportional to the severity of the AKI.