To test the hypothesis that HDL-P and HDL antioxidant capacity are associated with oxidative damage during surgery and postoperative AKI, we quantified and compared small, medium, large, and total HDL-P concentrations and PON-1 activity throughout the perioperative period and the nonesterified isofuran concentrations directly after surgery in 75 cardiac surgery patients who developed AKI and 75 matched control patients. The gene discussed is PON1; the disease is acute kidney injury.