The Value of Urinary Cystatin C Level to Predict Neonatal Kidney Injury

BACKGROUND: The role of urinary cystatin C to early predict acute kidney injury (AKI) in children and neonates remains uncertain. The present study aimed to assess and compare the level of urinary cystatin C in neonates with and those without AKI. METHODS: This cross-sectional study was performed on 55 available neonates who were involved by AKI and admitted to the neonatal department at Ali-Asghar hospital in Tehran in 2016. 97 neonates with jaundice and normal serum creatinine level were randomly selected as the control group. In both groups and on admission, the urine levels of cystatin C and creatinine were measured. RESULTS: The average urinary level of cystatin C was 162.87 ± 56.50 mmol/mole creatinine in the group with AKI and 68.06 ± 57.16 mmol/mole creatinine in the control group that was significantly higher in former group (p < 0.001). The measurement of cystatin C level in urine could predict kidney injury with a sensitivity of 98.2%, a specificity of 39.2%, a positive predictive value of 47.8%, a negative predictive value of 97.4%, and an accuracy of 60.5%. Assessment of the area under the receiver operating characteristic (ROC) analysis showed that measuring urinary cystatin C level could effectively discriminate kidney injury from normal kidney condition in neonates (AUC = 0.868, 95CI: 0.811 - 0.925, P < 0.001). The best cutoff value of urinary cystatin C level to predict kidney injury was shown to be 41.5 mmol/mole creatinine yielding a sensitivity of 98.2% and a specificity of 46.4%. CONCLUSION: Measurement of cystatin C in urine is an early sensitive method to diagnose neonatal kidney injury.