Serum neutrophil gelatinase associated lipocalin (NGAL) and cystatin C as early predictors of contrast-induced acute kidney injury in patients undergoing percutaneous coronary intervention

• Hypertension increases the risk of contrast-induced acute kidney injury (CI-AKI).
• Serum creatinine can detect CI-AKI after 48 h of contrast infusion.
• Serum NGAL can detect CI-AKI within 4 h of coronary angiography.
• Serum cystatin C can detect CI-AKI within 24 h of coronary angiography.
• Serum NGAL and cystatin C can act as early diagnostic markers of CI-AKI.

BackgroundContrast-induced acute kidney injury (AKI) is diagnosed by estimating serum creatinine at 48–72 h after diagnostic or interventional coronary angiography. It is too late for an early intervention. Neutrophil gelatinase associated lipocalin (NGAL) and cystatin C are novel markers of AKI. We determined the optimum cut-off level of NGAL and cystatin C in early diagnosis and prediction of AKI in patients undergoing coronary angiography followed by angioplasty.MethodsIn a nested case control study, serum NGAL, cystatin C by ELISA and serum creatinine by Jaffe's kinetic method were estimated at 0, 4, 24 and 48 h of coronary angiography followed by angioplasty in 30 cases who developed contrast-induced AKI and 30 subjects who did not develop AKI. eGFR was estimated for both cases and controls by the MDRD equation. ROC was used to determine the optimum cut-off.ResultsSerum NGAL increased sharply at 4 h after the procedure and then gradually declined to near normal level at 48 h in AKI cases. The rise in cystatin C peaked at 24 h and then declined but remained high till 48 h. In controls, they remained static. The optimum cut-off of serum NGAL and cystatin C was 155.2 ng/ml and 0.517 mg/l respectively at 4 h and 89.5 ng/ml and 0.99 mg/l respectively at 24 h of angiography. Odds ratio for hypertensives to develop AKI was 3.57 (CI: 1.2–11.1, p = 0.03).ConclusionSerum NGAL and cystatin C may act as early markers of contrast-induced AKI in patients undergoing percutaneous coronary intervention. Patients with hypertension are susceptible to develop contrast-induced AKI.