Significance of serum cystatin C level for early diagnosis of acute kidney injury in patients with acute-on-chronic liver failure

Objective To investigate the significance of serum cystatin C (CysC) level for the early diagnosis of acute kidney injury (AKI) in patients with acute- on- chronic liver failure (ACLF) . Methods Sixty patients with chronic hepatitis B- related ACLF and 60 patients with CHB, as well as 60 healthy controls, were included in the study. The ACLF patients were followed up until discharge, and serum samples were collected during hospital stay. Serum CysC level was measured by latex- enhanced immunoturbidimetric assay. The receiver operating characteristic (ROC) curves of serum CysC, creatinine (Cr) , and sodium levels for the diagnosis of AKI were drawn, and the areas under the ROC curves (AUCs) and optimal cut- off values were determined. For normally distributed measurement data, comparison between groups was made by one- way analysis of variance, and multiple comparisons were made by two- sided t test; otherwise, comparison between groups was made by Mann- Whitney U test. Enumeration data were analyzed by chi- square test. The Pearson correlation test was used for correlation analysis. The AUCs and optimal cut- off values were calculated by Medcal 12. 7. 1. 0. Results The serum CysC level in ACLF patients was 1050 ± 444 ng /ml, which was significantly higher than those in healthy controls (638 ± 275 ng /ml, P = 0. 016) and CHB patients (661 ± 225 ng /ml, P = 0. 028) ; for ACLF patients, serum CysC level was not significantly correlated with serum Cr level (r =0.311, P >0.05) , but showed a significant positive correlation with MELD score (r =0. 529, P <0. 01) . During hospital stay, 8 (13.3%) of ACLF patients developed AKI. The multivariate logistic regression analysis indicated that serum CysC level was the independent risk factor for AKI development in ACLF patients (OR = 1. 008, P = 0. 021) . The cut- off value of serum CysC level for the early diagnosis of AKI in ACLF patients was 1210 ng /ml. Conclusion Elevated serum CysC level may provide an early prediction of AKI development in ACLF patients with a normal serum Cr level during hospital stay.