Plasma neutrophil gelatinase-associated lipocalin (NGAL) and plasma cystatin C (CysC) as biomarker of acute kidney injury after cardiac surgery.

Acute kidney injury (AKI) is a common and serious condition that frequently occurs after cardiopulmonary bypass and other cardiac surgeries. The objective of this work is to evaluate the utility of new markers for kidney damage, plasma neutrophil gelatinase-associated lipocalin (NGAL) and plasma cystatin C (CysC) as early predictors of AKI after cardiac surgery. Fifty cardiac patients were recruited for this study, and they were divided into two groups of 25 patients each. Group I patients underwent coronary artery bypass graft (CABG) operation and Group II patients underwent valve replacement operation. Blood sample was taken for measurement of plasma CysC and NGAL by enzyme-linked immunosorbent assay. Plasma NGAL measurement in patients with AKI shows a highly significant rise at 3 and 6 h after surgery from its basal level (P <0.001). Plasma CysC measurement in patients with AKI is significantly higher at 6 h after surgery from its basal level (P <0.05). A statistically highly significant increase in plasma NGAL and CysC at 24 h after cardiac surgery in patients with AKI compared with patients without AKI (P <0.001). The sensitivity and specificity of NGAL at 3 h post-operative was 94.1% and 93.9% respectively, while plasma CysC sensitivity and specificity was 54.7% and 72.7%, respectively. After 6 h post-operative, NGAL sensitivity increased to 98.1% with slight decrease of the specificity to 91.9%, while CysC sensitivity and specificity increased to 75.2% and 75.8%, respectively. In conclusion, plasma NGAL and plasma CysC may be considered as early predictors of AKI after cardio-pulmonary bypass operations.