Neutrophil Gelatinase-Associated Lipocalin (NGAL) is a 25 kDa protein of the lipocalin superfamily expressed at low levels in a variety of tissues including neutrophils, kidney, and cardiomyocytes.

Serum Creatinine (SCr) is used for the diagnosis of AKI in the last few decades. However, SCr values are influenced by multiple non-renal factors such as age, gender, muscle mass and metabolism, dietary habits, medications, and hydration status. There is a considerable delay in increase of SCr after AKI and it does not reflect the actual decrease in glomerular filtration rate (GFR).

Clinical studies have shown that the expression of urine and serum NGAL increases significantly in AKI. NGAL is upregulated rapidly in the kidney very early after acute injury. Urine and blood NGAL have been demonstrated to be an early predictor of AKI in several clinical scenarios, including trauma cardiac surgery.