ABSTRACT

Acute kidney injury (AKI) is common following cardiopulmonary bypass (CPB). The aim of this study is to determine the accuracy of urinary neutrophil gelatinase-associated lipocalin (NGAL) levels following cardiac surgery to establish the severity of renal impairment as compared to serum creatinine levels.

A total number of 28 patients undergoing elective cardiopulmonary bypass were included. Diagnostic criteria of AKI was established in case of a percentage increase in serum creatinine concentration of >50%. Serum creatinine levels were recorded in the preoperative period before induction and in the postoperative period at 24, 48, and 72 hours. Urinary NGAL measurement was performed before induction and in the 4th postoperative hour. The duration of CPB surgery, hospital stay, and cross-clamp time were recorded.

Based on AKI criteria, subjects were grouped as AKI (n=11) and no AKI (n=19). Postoperative urinary NGAL levels were significantly higher in the group with AKI (11.8 ng mL-1 vs. 104.0 ng mL-1, p=0.003). In the AKI group, CPB time bypass (111.9 min vs. 82.7 min) and cross-clamp time (76.9 min vs. 59.1 min) were significantly higher. A cut-off of 25.5 ng mL-1 yielded a sensitivity of 81.82% and a specificity of 94.12% at the postoperative 4th hour with an AUC of 0.947 for predication of AKI.

Urine NGAL rose significantly much earlier as compared to serum creatinine levels in the early postoperative period. Although larger case series are needed, we are of the opinion that urinary NGAL measurements may be used as an early clinical marker of AKI following CPB.

Keywords: Acute kidney injury, neutrophil gelatinase-associated lipocalin, cardiopulmonary bypass