Urinary neutrophil gelatinase-associated lipocalin(NGAL)and serum cystatin C measurements for early diagnosis of acute kidney injury in children admitted to PICU

Background Acute kidney injury(AKI)is common in critically ill children with significant mortality and morbidity.Serum creatinine is an insensitive and late biomarker compared to newly proposed AKI biomarkers.Methods Prospective study in pediatric intensive care unit(PICU)over three months to compare between serum cystatin-C(s-Cys-C)and urinary neutrophil gelatinase-associated lipocalin(uNGAL)as AKI biomarkers at multiple time points with pediatric risk,injury,failure,loss,end-stage renal disease(pRIFLE)classification in diagnosing AKI.Results Forty children were recruited.Of these 40 children,22 developed AKI according to pRIFLE criteria.There was no significant difference between AKI and non-AKI in age(P=0.29).Post cardiac surgery,renal insult was the main cause of AKI(27.3%).There was a twofold increased risk of incident AKI in those patients with high baseline uNGAL at PICU admission and almost a fourfold increased risk in patients with high baseline s-Cys-C at PICU admission.uNGAL levels were highly predictive of AKI during the follow-up period[area under the curve(AUC)=0.76,95%confidence interval(CI)0.61-0.92].The cutoff point with the highest correctly classified proportion was 223 ng/mL(≥12 centiles)which correctly predict 80.0%patients with AKI,with a corresponding sensitivity of 72.7%and a specificity of 89.9%.AUC for s-Cys-C was 0.86(95%CI 0.75-0.97),and the highest correctly classified proportion was 1009μg/L(≥13 centiles);75%of patients with AKI,with a corresponding sensitivity of 63.6%and a specificity of 88.9%.Conclusion uNGAL and s-Cys-C predicts AKI early in critically ill children.