Cystatin C as a predictor of renal recovery and in hospital mortality in patients with acute kidney injury and liver cirrhosis

Background: Acute kidney injury (AKI) is a common and serious complication in patients with liver cirrhosis, with pre-renal AKI and acute tubular necrosis being the most frequent underlying causes. Cystatin C is a non-glycosylated 13 kDa protein that is consistently produced by all nucleated cells and has been suggested as a potential predictor of mortality in this patient population. The role of cystatin C in predicting renal recovery in these patients is not known and this was the aim of our study. Methods: This was a retrospective single center study that included hospitalized patients with liver cirrhosis who developed or were admitted with AKI and had serum cystatin C in their records from May 2017 to May 2023. The sociodemographic and laboratory data were retrieved from the data system. The in-hospital mortality, length of hospital stay, and renal recovery were recorded. Renal recovery was defined as a reduction in serum creatinine without needing dialysis on discharge. Results: This study included 209 patients with AKI and liver cirrhosis. Sixty-five patients (31%) died during hospital admission. The renal recovery was shown in 136 patients (65%). White blood cells, serum albumin, and peak serum cystatin C were the significant predictors for in-hospital mortality (p = 0.021, 0.013, and 0.001, respectively). Hypertension, serum albumin, baseline creatinine and baseline cystatin C were significant predictors of renal recovery in the studied patients (p = 0.017, 0.006, 0.030, and < 0.001, respectively). The cut-off value of baseline serum cystatin C for prediction of renal recovery was 2.62 with moderate sensitivity and specificity. Conclusion: In the current study, baseline serum cystatin C is a predictor of renal recovery in patients with AKI and liver cirrhosis. However, peak serum cystatin C is a predictor of mortality in these patients.