Multiple lines of evidence support a central role of iron in causing acute kidney injury (AKI), including the finding that prophylactic administration of iron chelators attenuates AKI in animal models. Patients undergoing cardiac surgery may be particularly susceptible to iron-mediated kidney injury due to the profound hemolysis that often occurs from cardiopulmonary bypass. The investigators will test in a phase 2, randomized, double-blind, placebo-controlled trial whether prophylactic administration of deferoxamine decreases the incidence of AKI following cardiac surgery.