Cystatin C: best biomarker for acute kidney injury and estimation of glomerular filtration rate in childhood cirrhosis

The objective of the study was to evaluate the diagnostic and prognostic role of serum cystatin C, urinary neutrophil gelatinase–associated lipocalin (NGAL), and renal resistive index (RRI) in AKI among pediatric cirrhotics. The study included cirrhotic children under 18 years of age. AKI was diagnosed as per Kidney Diseases–Improving Global Outcomes (KDIGO) guidelines. All patients underwent measurement of serum cystatin C, urinary NGAL, and RRI at baseline, 3 months, and 6 months. eGFR was calculated using both creatinine- and cystatin-based equations. Of the 247 cirrhotics admitted during the study, 100 gave consent and were included. Forty-one fulfilled the KDIGO definition of AKI of whom 22 showed resolution. Two of these children had a repeat AKI at 2 and 4 months after initial AKI; both resolved with medical management. On logistic regression analysis, serum cystatin C (OR: 544.8, 95% CI: 24.4–12170, p < 0.0005) and urinary NGAL (OR: 1.006, 95% CI: 1001–1.012, p = 0.019) were found to be significantly associated with AKI. Cystatin C alone was the best biomarker for diagnosing AKI in children with decompensation (OR: 486.7, p < 0.0005) or spontaneous bacterial peritonitis ( p = 0.02). eGFR calculated by serum cystatin C–based formulas was more reliable than that calculated by creatinine-based equations. Conclusion : Serum cystatin C is the best biomarker for diagnosis of AKI in pediatric cirrhotics, especially with decompensation and SBP. eGFR calculated on serum cystatin C–based equations is more reliable than creatinine-based ones. What is Known: • Acute kidney injury (AKI) is a common complication in cirrhotic adults . • Newer biomarkers have diagnostic and prognostic role in adult cirrhotics . What is New: • Serum cystatin C is a useful biomarker to identify acute kidney injury in cirrhotic children with decompensation . • Glomerular filtration rate calculation is more accurate by cystatin-based equations than creatinine-based equations.