Early detection of acute kidney injury by serum cystatin C in critically ill children.

BACKGROUND: We prospectively evaluated whether serum cystatin C (CysC) detected acute kidney injury (AKI) earlier than basal serum creatinine (Cr). METHODS: In 107 pediatric patients at high risk of developing AKI, serum Cr and serum CysC were measured upon admission. Baseline estimated creatinine clearance (eCCl) was calculated using a CysC-based glomerular filtration rate (GFR) equation from a serum Cr measured at the pediatric intensive care unit (PICU) entrance. RESULTS: The median age was 10 months (interquartile range, 3-36 months). Serum Cr, serum CysC, and eCCl (mean ± standard deviation [range]) were 0.5 ± 0.18 mg/dl (0.2-1.1 mg/dl), 0.53 ± 0.78 (0.01-3.7 mg/l), and 72.55 ± 28.72 (20.6-176.2) ml/min per 1.73 m(2), respectively. The serum CysC level in patients with AKI was significantly higher than children with normal renal function (p < 0.001). The values for the cut-off point, sensitivity, specificity, and the area under curve (AUC) were determined for CysC as 0.6 mg/l, 73.9 %, 78.9 %, and 0.92 [95 % confidence interval (0.82-1)], respectively, and for Cr the values were 0.4 mg/dl, 68 %, 46.2 %, and 0.39, [95 % confidence interval (0.24-0.54)], respectively. The receiver operating characteristics (ROC) curve analysis revealed that CysC had a significantly higher diagnostic accuracy than eCCl (p < 0.001). CONCLUSIONS: Our results identify that the sensitivity of serum CysC for detecting AKI is higher than that of serum Cr in a heterogeneous pediatric intensive care unit (PICU) population.

Urinary Neutrophil Gelatinase-Associated Lipocalin (NGAL) and Cystatin C in Early Detection of Pediatric Acute Kidney Injury; a Diagnostic Accuracy Study.

INTRODUCTION: There is a controversy regarding accuracy of neutrophil gelatinase-associated lipocalin (NGAL) and Cystatin C in early detection of acute kidney injury (AKI). The present study aimed to compare the diagnostic value of two biomarkers in this regard. METHOD: In the present diagnostic accuracy study, all children between the ages of 1 month to 14 years were entered. Pediatric Risk, Injury Failure, Loss, End-stage renal disease (pRIFLE) criteria was used for identification of children with AKI as the reference test. Blood samples were taken from all patients at baseline and 48 hours after admission to assess serum creatinine and Cystatin C level. In addition, a urine sample was obtained within 6 hours of admission in order to measure NGAL level. In the end, area under the receiving operating characteristics (ROC) curve, sensitivity, and specificity of urine NGAL (uNGAL) and Cystatin C in early detection of AKI were compared. RESULTS: Data from 96 children with the mean age of 27.31±36.24 months were entered (56.25% girls). Area under the ROC curve of uNGAL level in diagnosis of AKI in children was 0.91 (95% CI: 0.80 to 1.00) and area under the ROC of Cystatin C was 0.90 (95% CI: 0.77 to 1.00). Both tests had the same value in diagnosis of AKI (p=0.89). The best cut-off point of uNGAL for diagnosing AKI was 125 mg/L. uNGAL had a sensitivity and specificity of 0.92 (0.62 to 0.99) and 0.69 (0.57 to 0.78), respectively. The best cut-off point of serum Cystatin C level was 0.4 mg/L. Cystatin C had a sensitivity and specificity of 0.92 (0.62 to 0.99) and 0.64 (0.52 to 0.74), respectively. CONCLUSION: The present study showed that uNGAL level has the same value as serum Cystatin C level in early diagnosis of AKI.