Value of serum and urinary neutrophil gelatinase-associated lipocalin and cystatin C in diagnosis of liver cirrhosis complicated by acute kidney injury

Objective To investigate the value of serum neutrophil gelatinase-associated lipocalin (sNGAL) , urinary neutrophil gelatinase-associated lipocalin (uNGAL) , and serum cystatin C (CysC) in the early diagnosis of acute kidney injury (AKI) in patients with liver cirrhosis.Methods A total of 236 patients with liver cirrhosis and normal renal function who visited The Red Cross hospital of Hannan District from January 2015 to March 2017 were enrolled, and according to the presence or absence of AKI within 48 hours after admission, these patients were divided into AKI group with 78 patients and non-AKI group with 158 patients.Another 100 healthy subjects who underwent physical examination were enrolled as control group.ELISA was used to measure sNGAL, uNGAL, and serum CysC, and serum creatinine (SCr) and glomerular filtration rate (GFR) were compared between groups.A one-way analysis of variance was used for comparison of continuous data between multiple groups, and the SNK-q test was used for further comparison between two groups.A Pearson correlation analysis was also performed, and the receiver operating characteristic (ROC) curve was used to evaluate the diagnostic value of these indices.Results At 48 hours after admission, there were significant differences in sNGAL, uNGAL, and CysC between the AKI group and the non-AKI group/control group (all P<0.05) .The patients in the AKI group were stratified by AKI stage based on the criteria for kidney injury, and the patients with a higher stage had significantly higher levels of sNGAL and uNGAL than those with a lower stage (both P<0.05) .The levels of sNGAL, uNGAL, and CysC started to increase at 6 hours after admission, while Scr and GFR started to change at 48 hours after admission, i.e., sNGAL and uNGAL increased significantly earlier than Scr and GFR (P<0.05) .In the AKI group, sNGAL, uNGAL, and CysC were positively correlated with SCr (r=0.650, 0.681, and 0.581, all P<0.05) .According to the ROC curve analysis, sNGAL had an area under the ROC curve (AUC) of 0.845±0.435, an optimal cut-off value of 542.68 μg/L, a sensitivity of 0.824, and a specificity of 0.794, uNGAL had an AUC of 0.836±0.326, an optimal cut-off value of 75.12 μg/L, a sensitivity of 0.816, and a specificity of 0.766, and CysC had an AUC of 0.818±0.267, an optimal cut-off value of 1.48 mg/L, a sensitivity of 0.808, and a specificity of 0.732.Conclusion NGAL and CysC can be used as indices for the early diagnosis of AKI and have great significance in evaluating renal injury and developing treatment measures for patients with liver cirrhosis.