ROLE of NEUTROPHIL GELATINASE ASSOCIATED LIPOCALIN as an EARLY BIOMARKER of ACUTE KIDNEY INJURY in CRITICALLY ill PATIENTS

Abstract

AKI is characterized by a rapid (hours to weeks) decline in GFR and retention of nitrogenous waste products such as BUN and creatinine. The most recent definitions proposed by the Acute Dialysis Quality Initiative (ADQI), RIFLE and AKIN have been based on rises in serum creatinine or reductions in urine output. These definitions aimed to promote the earlier detection and recognition of AKI triggering appropriate treatment prior to progressive injury and kidney failure. Based on RIFLE and AKIN criteria, up to 20% of hospitalized patients may develop AKI. 35%-40%of patients who are critically ill will develop AKI, 5% will develop sever AKI requiring RRT. Among the subgroup of patients who survive initial dialysis, less than 25% require long-term dialysis. Currently, the mortality rate for hospital-acquired AKI ranges between 40% up to70% (in ICU more than non- ICU patients) and is directly correlated to the severity of the patient's other disease processes. The etiology of AKI in general may be due to decrease renal perfusion (pre-renal causes), injury to the kidney glomeruli, tubules or interstitium (intra-renal causes) or obstruction of urinary outflow (post-renal causes). However, in ICU about 80% of AKI is due to intra-renal causes mostly due to ATN. A stepwise evaluation approach to the patient with AKI is recommended. A comprehensive history and thorough physical examination suggest the diagnosis in most patients and the probable cause which is important for further evaluation and management. Laboratory investigation like urine analysis, urinary indices or biomarkers and imaging investigations can be helpful in diagnosis of AKI and its etiology. Renal biopsy is reserved for patients in whom pre-renal and post-renal causes have been excluded and the cause of intrinsic renal AKI is unclear. Many biomarkers have been evolved e.g IL-18,KIM-1and (NGAL). The aim of these biomarkers in AKI to diagnose AKI earlier, indicate the location of the injury, need for renal replacement therapy and monitor the response to interventions. In experimental and clinical studies, NGAL is one of the most studied and promising biomarkers for early diagno- sis of AKI. There is increasing evidence that NGAL is not only a marker of AKI but also a predictive factor for severity, mortality and hospital stay.