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 neonatal department at Ali-Asghar hospital in Tehran in 2016. Ninety-seven 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 mean 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.