Neutrophil gelatinase--associated lipocalin predicts acute kidney injury in patients undergoing liver transplantation.

Postoperative acute kidney injury (AKI) increases morbidity and mortality after liver transplantation (LT). Novel methods of assessing AKI including cystatin C (CyC) and neutrophil gelatinase-associated lipocalin (NGAL) have been identified as potential markers of AKI. We compare the ability of standard renal markers (serum creatinine [sCr], estimated glomerular filtration rate [eGFR] and intensive therapy unit organ failure scores with CyC and NGAL to predict AKI within the first 48 hours after LT. 95 patients (median age 50 [interquartile range = 41-59], 60% male) underwent LT (25% with acute liver failure). AKI was defined according to the Acute Kidney Injury Network criteria. Severe AKI was classified as ≥stage 2. NGAL (urine [u] and plasma [p]) and CyC concentrations taken immediately after transplantation on admission to the Liver Intensive Care Unit were compared with standard markers of renal function. Predictive ability was assessed using the area under the curve generated by receiver operator characteristic analysis (AUROC) and logistic regression. Day 0 sCr, uNGAL, pNGAL, CyC, and eGFR predicted AKI as did SOFA (Sequential Organ Failure Assessment) and APACHE II (Acute Physiology and Chronic Health Evaluation II) scores. APACHE II and pNGAL were the most powerful predictors of severe AKI (APACHE II AUROC = 0.87 [0.77-0.97], P < 0.001; pNGAL AUROC = 0.87 [0.77-0.92], P < 0.001). Using multivariate logistic regression, APACHE II (odds ratio 1.64/point [95% confidence interval = 1.22-2.21, P = 0.001] and pNGAL [odds ratio = 1.01/ng/mL [95% confidence interval = 1.00-1.02], P = 0.002) retained independent significance. A "renal risk score" using APACHE II > 13 and pNGAL > 258 ng/mL was calculated with a score of ≥1 having a 100% sensitivity and 76% specificity for severe AKI. In conclusion, a combination of NGAL and APACHE II predicts AKI with high sensitivity and specificity after LT.