Evaluation of Neutrophil Gelatinase-associated Lipocalin (NGAL) in Early and Evolving Acute Kidney Injury

4.2.1 Inclusion Criteria 1. Male or female scheduled for cardiovascular surgery (other than cardiac transplant) requiring cardiopulmonary bypass 2. 18 years of age or older i. The first approximately 150 to200 patients enrolled must have: • A Prediction of Acute Renal Failure Score ≥ 5 (see Reference 18 and Appendix B) ii. The subsequent patients enrolled must have one or more of the following risk factors for post-bypass renal injury: * Age \> 70; * Pre-operative creatinine \> 1.4 mg/dL; * NYHA Class 3 or 4 heart failure or left ventricular ejection fraction \< 35%; * Insulin-dependent diabetes mellitus; * Undergoing cardiac valve surgery; * History of previous cardiac surgery. Exclusion Criteria: * Age \< 18 years * Inability to obtain Informed Consent from patient or representative * Prisoners or other institutionalized or vulnerable individuals * Participation in an interventional clinical study within the previous 30 days * History of previous renal transplantation * Stage 5 chronic kidney disease (estimated GRF\<15 mL/min/1.73m2) (See Appendix C) * Known or suspected ongoing pre-operative acute renal failure due to any cause, including pre-renal, intrinsic renal or post-renal (obstructive) etiologies (as evidenced by increasing serum creatinines or oliguria pre-operatively) * Already receiving dialysis, in imminent need of dialysis or considered highly likely to need dialysis in the immediate post-operative period for fluid management * Any known or suspected renal ischemic insult(such as cardiac arrest)or nephrotoxic insult(other than intravascular contrast procedure) during the 48 hours prior to surgery * Known or suspected infection with human immunodeficiency virus (HIV), hepatitis C virus (HCV)infection, hepatitis B virus (HBV) infection or other infectious hepatitis * Pre-operative hematocrit \<25%, recent blood transfusions have been administered to maintain hematocrit \>25% or any other contraindication to obtaining the study-specified blood samples * Undergoing cardiac transplantation