Serum cystatin C for acute kidney injury evaluation in children treated with aminoglycosides.

BACKGROUND: Serum cystatin C (CysC) is a more accurate glomerular filtration rate marker than serum creatinine (SCr) and may rise more quickly with acute kidney injury (AKI).

METHODS: We performed a prospective cohort study of 81 non-critically ill children during 110 aminoglycoside (AG) treatments. We calculated area under the curve (AUC) for CysC to diagnose SCr-defined AKI and predict persistent AKI. SCr-AKI definition was based on the Kidney Disease: Improving Global Outcomes (≥stage 1: ≥50 % or 26.5 μmol/l SCr rise from baseline; stage 2: SCr doubling); CysC-AKI was based on a modified version using CysC rise.

RESULTS: SCr-AKI and CysC-AKI developed in 45 and 48 % treatments, respectively. CysC rise predicted stage 1 (AUC = 0.75, 95 % CI 0.60-0.90) and 2 (AUC = 0.85, 95 % CI 0.75-0.95) SCr-AKI 2 days before SCr-AKI attainment. The best combined sensitivity/specificity for percent CysC rise to predict stage 1 SCr-AKI was with a 44 % CysC rise (sensitivity = 65 %, specificity = 83 %). CysC rise on day of SCr-AKI development was associated with SCr-AKI ≥48 h (AUC = 0.73, 95 % CI 0.56-0.90) and ≥50 % persistent SCr rise at treatment end (AUC = 0.76, 95 % CI 0.61-0.90).

CONCLUSIONS: CysC is as an early AKI biomarker and predictive of persistent AKI on aminoglycoside treatment.