Biomarkers for acute kidney injury: is NGAL ready for clinical use?

The RIFLE (Risk, Injury, Failure, Loss, and End-stage kidney disease) criteria were introduced in 2004, defining the clinical stage of acute kidney injury (AKI) and outcome measures based on serum creatinine, glomerular filtration rate, and urine output. However, a growing body of evidence suggests that these markers are insufficient in drawing an accurate illustration of kidney injury. Indeed, mortality and morbidity remain high in AKI, suggesting that accuracy and speed of patient evaluation are lacking. A great deal of evidence indicates that neutrophil gelatinase-associated lipocalin (NGAL) is a sensitive and specific early marker of various etiological classes of AKI and would be highly valuable in conjunction with existing markers of AKI for better classifying renal injury as well as dysfunction (kidney attack). Improvements in diagnosis, risk identification, stratification, prognosis, and therapeutic monitoring will benefit clinical decision-making in the individualized bundling of therapies and ongoing patient management. In particular, kidney protection and AKI prevention may become feasible if an earlier and more accurate diagnosis is made for AKI. Here, we discuss the opportunity to consider whether NGAL is ready for routine clinical use in a number of etiologies of AKI.