acute kidney failure is financially beneficial and favorable for preventative health measures. More than 10% of people in the United States will develop some kind of chronic kidney disease (CKD), with higher incidences for individuals that suffer from obesity, elevated cholesterol, and a family history of CKD. There is no point of return once there is a significant injury to the kidney; therefore, early diagnosis of kidney injury is important for preventing AKI. Using NGAL as a biomarker can lower hospital costs because fewer patients will reach a critical stage in kidney injury. Ultimately, diagnosis of AKI with NGAL can reduce the time a patient stays in a hospital. For example, the early diagnosis of AKI with NGAL as a biomarker can help a patient avoid kidney dialysis. Laboratory measurement Renal expression of NGAL increases in the kidneys after injury for a variety of reasons. The level of NGAL in the urine and plasma increases within 2 hours of kidney injury. It is possible to measure NGAL in serum or urine in the range of 25 to 5,000 ng/mL by current laboratory tests. Low levels for NGAL have been considered to be 20 ng/mL, medium levels 200 ng/mL, and high levels 1200 ng/mL. A study on children with pediatric cardiopulmonary bypass operations showed that urinary NGAL concentrations above 50 ng/mL 2 hours after surgery is indicative of serum creatinine levels 50% over basal values. Normally, children tend to have almost undetectable levels of NGAL. Therefore, studies that include children are considered to be “pure.” Adult patients presenting for cardiopulmonary bypass surgery are not considered to be “pure” in NGAL studies because adults often have other disorders such as inflammatory conditions, which can cause slight increases in NGAL. AKI studies investigating the use of NGAL as a biomarker often compare serum creatinine and NGAL production. Unfortunately, serum creatinine production is variable and can reflect hemodynamic variation in the glomerular filtration rate formerly known as prerenal azotemia; therefore, the comparison is not always reliable because creatinine and NGAL measure different components of renal (dys)function. The demonstration that NGAL does not rise in the setting of transient changes in creatinine can help clinicians determine whether changes in creatinine reflect kidney damage or rather only non specific or mild functional changes in kidney function. Lipocalin-2 (NGAL) is typically assessed for clinical or research purposes using ELISA or immunoturbidimetric assays. References Lipocalins