Neutrophil gelatinase-associated lipocalin (NAGL): a novel biomarker for acute kidney injury]

The incidence of both acute and chronic kidney diseases is persistently increasing and is reaching epidemic proportions. Early therapeutic intervention may significantly decrease the morbidity and mortality rates among these patients. However, the lack of early non-invasive biomarkers has hampered our ability to diagnose kidney diseases as early as possible, and subsequently, to initiate timely, effective, and appropriate treatment. Until recently, no biomarker for kidney disease, except for creatinine was available to clinicians in general and nephrologists in particular. Unfortunately, creatinine is an unreliable indicator during acute and chronic changes in kidney function, since serum creatinine concentrations can vary widely with age, gender, muscle mass, muscle metabolism, medications and hydration status. Secondly, serum creatinine concentrations may not change until a significant amount of kidney function (50-60%) has already been lost. In the last few years various specific biomarkers for kidney diseases were discovered and the most reliable representative is neutrophil gelatinase-associated lipocalin (NGAL), which is the focus of this review. Several studies have demonstrated that plasma and urinary NGAL levels increase two hours after the induction of acute kidney injury (AKI) in several clinical situations such as cardiac surgery, radiocontrast nephropathy, kidney transplantation, hemolytic uremic syndrome and critically ill patients in intensive care unit. Serum and urine concentrations of NGAL increase before those of creatinine, making this biomarker a powerful tool for early detection of renal disease, thus hopefully to reduce the high mortality rate among patients with AKI.