Serum Cystatin C for the Diagnosis of Acute Kidney Injury in Patients Admitted in the Emergency Department

Background. Early diagnosis of acute kidney injury (AKI) at emergency department (ED) is a challenging issue. Current diagnostic criteria for AKI poorly recognize early renal dysfunction and may cause delayed diagnosis. We evaluated the use of serum cystatin C (CysC) for the early and accurate diagnosis of AKI in patients hospitalized from the ED. Methods. In a total of 198 patients (105 males and 93 females), serum CysC, serum creatinine (sCr), and estimated glomerular filtration rate (eGFR) were calculated at 0, 6, 12, 24, 48, and 72 hours after presentation to the ED. We compared two groups according to the presence or absence of AKI. Results. Serial assessment of CysC, sCr, and eGFR was not a strong, reliable tool to distinguish AKI from non-AKI. CysC > 1.44mg/L at admission, both alone (Odds Ratio = 5.04; 95% CI 2.20-11.52; P < 0.0002) and in combination with sCr and eGFR (Odds Ratio = 5.71; 95% CI 1.86-17.55; P < 0.002), was a strong predictor for the risk of AKI. Conclusions. Serial assessment of CysC is not superior to sCr and eGFR in distinguishing AKI from non-AKI. Admission CysC, both alone and in combination with sCr and eGFR, could be considered a powerful tool for the prediction of AKI in ED patients.