Comparison of the value of plasma and urine cystatin-C and neutrophil gelatinase-associated lipocalin levels in prediction of acute kidney injury in sepsis

Introduction

The aim was to study the impact of inflammation/sepsis on the concentrations of cystatin-C and neutrophil gelatinase-associated lipocalin (NGAL) in plasma and urine in adult ICU patients and to estimate the predictive properties of cystatin-C and NGAL in plasma and urine for early detection of acute kidney injury (AKI) in patients with sepsis.

Methods

The RIFLE class for AKI was calculated daily, while plasma and urinary Cys-C and NGAL were determined on days 0 and alternate days until ICU discharge. Test characteristics were calculated to assess the diagnostic performance of urinary and plasma Cys-C and NGAL. The diagnostic and predictive performances of the markers were assessed from the area under the receiver operator characteristic curve (AUC).

Results

One hundred and twenty-eight patients were studied, and three groups were defined: normal (n = 41); sepsis (n = 45); and sepsis and AKI (n = 42). AUCs for diagnosis of AKI using plasma and uCys-C were as follows: 0.89 (P < 0.0001) and 0.91 (P < 0.0001) Cut-off points for AKI for plasma and uCys-C were 1.7 mg/l (sensitivity: 83%, specificity: 77%)and 0.11 mg/l (sensitivity = 92%, specificity = 80%), respectively. Urinary NGAL showed fair discrimination for AKI diagnosis (AUC = 0.85). Although plasma NGAL performed less well (AUC = 0.58).

Conclusion

Plasma and urinary Cys-C are useful markers in predicting AKI in sepsis. pNGAL is raised in patients with sepsis, and should be used with caution as a marker of AKI in ICU patients with sepsis. uNGAL is more useful in predicting AKI as the levels are not elevated in septic patients without AKI.