Utility of Urinary Neutrophil gelatinase associated lipocalin (NGAL) in decompensated cirrhosis

Background and Aims: Renal failure occurring in the setting of cirrhosis increases mortality by more than threefold. Serum creatinine, the conventional marker for renal dysfunction has inherent limitations in identifying and categorizing renal dysfunction in patients with chronic liver disease (CLD). Neutrophil gelatinase associated lipocalin (NGAL) is a novel biomarker which gets upregulated as early as 2-6 hours following the insult to renal tubules. In this study, we aim to check the utility of uNGAL to identify the different phenotypes of renal dysfunction in patients with CLD. We also intend to assess the utility of NGAL to predict 90-day transplant-free survival in patients with CLD. Methods: A total number of 120 adult patients, with cirrhosis of liver were recruited. Those with pre-existing renal parenchymal disease, receiving nephrotoxic medications, spontaneous bacterial peritonitis, septic shock, proteinuria, hematuria, urinary tract infection and anuria were excluded. Urine samples for NGAL was measured at admission and at 48 hours thereafter. Patients were followed up for 90 days post admission. Results: Among the study population, 16 patients (13.3%) had normal kidney function, 43 (35.8%) had prerenal azotemia and 54 (45%) had Hepatorenal Syndrome (HRS -AKI) and 7 (5.8%) had acute tubular necrosis (ATN). Urinary NGAL (uNGAL) levels were considerably lower in patients with normal kidney function and prerenal azotemia. An uNGAL level of 124 ng/ml on admission could distinguish severe forms of renal injury, with a sensitivity of 86% and specificity of 84%. The non survivors had higher uNGAL levels at admission [209.6 ng/ml (118.7-376.8) vs. 123 (33.6-344.3); P = 0.013].The receiver operated curves for uNGAL and serum creatinine at admission did not show any significant difference for predicting 90 day mortality (AUC for uNGAL: 0.632 vs 0.580 for serum creatinine; difference in AUC 0.053, P value 0.17). Conclusion: uNGAL levels are elevated in patients with HRS-AKI and ATN. A higher uNGAL level at admission was suggestive of severe renal dysfunction. An elevated uNGAL on admission is associated with inferior survival. However, uNGAL is not superior to serum creatinine in predicting 90-day mortality.