Consequences of acute kidney injury on remote organ functions. There is increasing evidence that acute kidney injury directly contributes to remote injury in the heart, lung, brain, liver, immunologic, and other organ systems. In the hepatic system, acute kidney injury causes intestinal barrier breakdown and greater gut translocation and delivery of endotoxins and microorganisms to the portal system. This results in hepatic inflammation and apoptosis along with hepatic overproduction and systemic release of proinflammatory cytokines. Acute kidney injury is also associated with cerebral dysfunction, including uremic encephalopathy. Activation of neuroinflammatory cascade results in increase in vascular permeability and breakdown of blood–brain barrier. In the cardiac system, acute kidney injury is associated with cardiorenal syndrome, which is a state of concomitant heart and kidney failure. Suggested mechanisms of acute kidney injury–induced cardiac dysfunction include fluid overload and uremia-induced decrease in myocardial contractility. In the pulmonary system, the remote effect of acute kidney injury is due to activation of inflammatory cascade leading to an increase in pulmonary vascular permeability and lung neutrophil infiltration. This leads to accumulation of fluid within the lung tissue, causing pulmonary edema. In the immunologic system, acute kidney injury has a profound impact on humoral and cellular immunity and overall immunocompetence. This is due to a combination of increase in oxidative stress, impaired clearance of the reticuloendothelial system, and decreased clearance of circulating cytokines, leading to higher rate of infections in patients with acute kidney injury. CHF, congestive heart failure; NYHA, New York Heart Association classification of heart failure.