Serum cystatin-C as a marker of acute kidney injury in the newborn after perinatal hypoxia/asphyxia.

We evaluated cystatin-C (cysC) in the umbilical blood as a predictor of acute kidney injury (AKI) after perinatal hypoxia/asphyxia compared with creatinine (Cr). One hundred full-term newborns were enrolled in the study (50 in a group affected by perinatal hypoxia/asphyxia [AS] and 50 controls). CysC and Cr were measured in blood samples from the umbilical cord at birth (cysC-umb and Cr-umb) and from a peripheral vein 3 days later (cysC-3 and Cr-3). At birth, the mean level of cysC in healthy term babies was found to be 1.39 ± 0.19 mg/L and 1.34 ± 0.21 mg/L after 3 days of life, not significantly decreased (P = 0.137). The mean of cysC in the AS group was 2.12 ± 0.53 mg/L in cord blood and 1.56 ± 0.32 g/L in day 3 blood samples, also decreased (P < 0.001) and different from the control (P < 0.001). Cr levels, determined simultaneously at birth were different (P = 0.001) between the control (62.74 ± 12.84 μmol/L) and AS (72.60 ± 15.55 μmol/L) group, significantly decreased after 3 days in both groups (P < 0.001). The receiver-operating characteristic curve analysis, comparing AS and the control group, showed area under the curve for cysC-umb, cysC-3, Cr-umb and Cr-3 (0.918; 0.698; 0.692; 0.660). The highest diagnostic accuracy was achieved with a chosen cut-off for cysC-umb of 1.67 mg/L (sensitivity of 84.0%, specificity of 90.0%) or 1.69 mg/L (sensitivity of 82.0%, specificity of 94.0%). Our results indicate serum CysC is a more sensitive marker of glomerular filtration rate than Cr in the newborns.