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Objective: The purpose of this study was to compare urinary neutrophil gelatinase-associated lipocalin (NGAL) levels in off-pump and on-pump coronary artery bypass graft (CABG) surgery., Design: A matched cohort study., Setting: A tertiary university hospital., Participants: Thirty adult patients undergoing CABG surgery without cardiopulmonary bypass (off-pump) matched to 30 patients with on-pump CABG surgery by age, preoperative serum creatinine, Parsonnet score, ejection fraction, body mass index, and number of coronary artery grafts., Interventions: None, observational., Measurements and Main Results: Urinary NGAL, a novel, highly sensitive biomarker for renal injury, was measured before and immediately after surgery and then 3, 18, and 24 hours later. There were no differences in urinary NGAL at any time point between patients subjected to off-pump or on-pump CABG surgery; the peak urinary NGAL in patients who underwent off-pump CABG surgery was 94.7 +/- 30.9 ng/mL compared with 122.7 +/- 57.0 ng/mL in patients with on-pump CABG surgery (p = 0.6). Peak serum creatinine and the incidence of acute kidney injury also were not different between the groups., Conclusions: Urinary NGAL was not different in patients undergoing off-pump and on-pump CABG surgery despite a very good match between the groups with respect to pre- and intraoperative risk factors.

Background: Neutrophil gelatinase-associated lipocalin (NGAL) is proposed as an early marker of kidney injury. We report the association of urinary NGAL with indexes of intraoperative renal hypoperfusion (cardiopulmonary bypass time and aortic cross-clamp time) and acute kidney injury (AKI) after adult cardiac surgery., Study Design: Diagnostic test accuracy., Setting & Participants: Adult cardiac surgical patients (n = 426) in a single center from 2004 to 2006., Index Test: Urinary NGAL immediately and 3, 18, and 24 hours after cardiac surgery, using an enzyme-linked immunosorbent assay., Reference Test or Outcome: Serum creatinine-based definition for AKI (increase in serum creatinine from preoperative values by >50% or >0.3 mg/dL within 48 hours)., Results: Mean urinary NGAL level was 165 +/- 663 (SD) ng/mL preoperatively, peaked immediately after cardiac surgery at 1,490 +/- 102 ng/mL, and remained significantly higher 3, 18, and 24 hours after surgery. 85 patients (20%) developed AKI. Areas under the receiver operating characteristic curve for urinary NGAL immediately after and 3, 18, and 24 hours later as a predictor for AKI were 0.573 (95% confidence interval [CI], 0.506 to 0.640), 0.603 (95% CI, 0.533 to 0.674), 0.611 (95% CI, 0.544 to 0.679), and 0.584 (95% CI, 0.510 to 0.657), respectively. Urinary NGAL, but not serum creatinine, level correlated significantly with cardiopulmonary bypass and aortic cross-clamp times. Areas under receiver operating characteristic curves for cardiopulmonary bypass time and aortic cross-clamp time to predict AKI were 0.592 (95% CI, 0.518 to 0.666) and 0.593 (95% CI, 0.523 to 0.665), respectively., Limitations: Limited sensitivity of changes in serum creatinine levels for kidney injury., Conclusions: Urinary NGAL has limited diagnostic accuracy to predict AKI defined by change in serum creatinine after cardiac surgery.