plasma neutrophil gelatinase–associated lipocalin (ngal) and plasma cystatin c (cyc) as biomarkers of acute kidney injury after cardiac surgery

acute kidney injury (AKI) occurs frequently after cardiopulmonary bypass (CPB) and cardiac surgery and is associated with increased morbidity, mortality, and duration of intensive care treatmentOften AKI manifests as a transient rise in serum creatinine and is managed conservatively; however, a group of patients, often with significant comorbidity, require temporary renal replacement therapySerum creatinine, the currently accepted ‘gold standard’ to diagnose AKI, is a delayed and inadequate marker of acute changes in renal function. In AKI, serum creatinine elevation that reflects the development and severity of kidney damage does not occur until days after renal tubular injury has begun.Although serum creatinine is routinely used as a marker of renal function, it performs poorly in the immediate postoperative period. This is mainly due to hemodilution resulting from CPBThis often results in a fall in serum creatinine even in the presence of significant renal injury. More importantly, serum creatinine usually rises only after 24–36 hours after renal tubular damage and therefore does not fulfil the criteria for an early predictive biomarker of AKIThus, there is a need for rapidly available, sensitive, and specific biomarkers for AKI that would allow early prediction at a time when intensive care optimization can be performedThis work aimed to to evaluate plasma level of NGAL and Cystatin C as early predictors of AKI after cardiac surgery.