Serum cystatin C as an earlier predictor of acute kidney injury than serum creatinine in preterm neonates with respiratory distress syndrome.

In this study, we aimed to evaluate serum cystatin C (sCysC) as an early predictor of acute kidney injury (AKI) in preterm neonates with respiratory distress syndrome (RDS). Sixty preterm neonates diagnosed with RDS and 40 healthy controls (28-36 weeks) admitted to the neonatal Intensive Care Unit were investigated. AKI was defined on the 3rd day of life (DOL-3) as an increase in serum creatinine (sCr) of >0.3 mg/dL from baseline (the lowest previous sCr). sCysC levels were measured on DOL-1, -3 and -7. Of the 60 neonates with RDS, 24 (40%) developed AKI. Five patients (79.17%) were classified as AKI Network (AKIN-1) and 19 patients (20.83%), as AKIN-2. At DOL-3, the mean sCysC values were significantly higher among neonates with RDS and AKI (1.68 ± 0.37) compared with controls (0.79 ± 0.83) and those with RDS and no AKI (0.85 ± 0.20) (P <0.001). sCysC levels significantly increased among neonates with AKI from DOL-3 to DOL-7 (P = 0.002). The sCr values showed no significant difference between those with RDS with AKI, RDS, and no AKI or control groups at DOL-1 and -3. Only as late as DOL-7, the mean values of sCr were higher among neonates with AKI compared with no AKI and controls (P <0.001). The receiver operating characteristic curves area under the curve was 0.97 for predicting the development of AKI within 72 h (P = 0.001). With the best cutoff value of ≥1.28 mg/L, the sensitivity and specificity of sCysC for detecting AKI within 72 h were 100 and 83.3%, respectively. In conclusion, sCysC is an early marker for AKI in neonates with RDS.