PLASMA NEUTROPHIL GELATINASE–ASSOCIATED LIPOCALIN (NGAL) AND PLASMA CYSTATIN C (CYC) AS BIOMARKER OF ACUTE KIDNEY INJURY AFTER CARDIAC SURGERY

Abstract

Introduction: 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
treatment.Serum 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.
CyC is excreted by glomerular filtration, then undergoes essentially complete tubular reabsorption and
catabolism (without secretion), so that it is not normally found in urine in significant amounts. NGAL, a
25 kDa member of the lipocalin family, is markedly upregulated in the early postischemic mouse and rat
kidney. Serum and urine NGAL levels are elevated earlier than serum creatinine in the setting of delayed
graft function following kidney transplantation and percutaneous coronary intervention
Objective: the aim of work is to study if plasma NGAL and plasma Cystatin C could be an early
predictors of AKI after cardiac surgery
Subject and methods: fifty patients were included in this study, they were divided into two main groups;
Group(I) 25 patients underwent CABG operation ,Group(II) 25 patients underwent valve replacement
operation then classified after the operation to AKI group and NO AKI group according to the RIFLE
criteria.
Result: plasma NGAL measurement in patient with AKI shows a highly significant rise at 3and 6 hours
after surgery from basal level. Plasma cysc measurement in patient with AKI shows an non significant
rise at 3 hours that become significantly at 6 hours after surgery from basal level. a statistically highly
significant increase in the mean value of plasma NGAL and cysc at 24 hour after cardiac surgery in
patient with AKI compared with patients without AKI.serum creatinine show a statistical significant
increase in patient with AKI compared with patient without AKI.the sensitivity and specificity of NGAL
at 3h postoperative was 94.1% and 93.9% respectively. It was high in compared to plasma CysC 54.7%
and 72.7 % respectively. After 6 hour postoperative; NGAL sensitivity increased to 98.1% with slight
decrease of the specificity to 91.9% , which was associated with increased CysC sensitivity and
specificity to 75.2% and 75.8% respectively.
Conclusion and Recommendations:-
In conclusions, plasma NGAL and plasma Cystatin C maybe considered as early predictors of AKI after
cardio-pulmonary bypass operations. using plasma NGAL basally and 3houres after cardiopulmonary
bypass as early renal biomarker of acute kidney injuery. using serum Cystatin C basally and 6houres after
cardiopulmonary bypass as early renal biomarker of acute kidney injuery. Further studies are
recommended using large number of patient.