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

BACKGROUND

Contrast-induced acute kidney injury (AKI) is diagnosed by estimating serum creatinine at 48-72h 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.

METHODS

In 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 48h 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.

RESULTS

Serum NGAL increased sharply at 4h after the procedure and then gradually declined to near normal level at 48h in AKI cases. The rise in cystatin C peaked at 24h and then declined but remained high till 48h. In controls, they remained static. The optimum cut-off of serum NGAL and cystatin C was 155.2ng/ml and 0.517mg/l respectively at 4h and 89.5ng/ml and 0.99mg/l respectively at 24h of angiography. Odds ratio for hypertensives to develop AKI was 3.57 (CI: 1.2-11.1, p=0.03).

CONCLUSION

Serum 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.