Prerenal azotemia in congestive heart failure

Prerenal failure is used to designate a reversible form of acute renal dysfunction. However, the terminology encompasses different conditions that vary considerably. The Acute Kidney Injury Network group has recently standardized the acute kidney injury (AKI) definition and classification system; however, these criteria have not determined specific diagnostic criteria to classify prerenal conditions. The difference in the pathophysiology and manifestations of prerenal failure suggests that our current approach needs to be revaluated. Several mechanisms are recognized as contributory to development of a prerenal state associated with cardiac failure. Because of the broad differences in patients' reserve capacity and functional status, prerenal states may be triggered at different time points during the course of the disease. Prerenal state needs to be classified depending on the underlying capacity for compensation, the nature, timing of the insult and the adaptation to chronic comorbidities. Current diagnosis of prerenal conditions is relatively insensitive and would benefit from additional research to define and classify the condition. Identification of high-risk states and high-risk processes associated with the use of new biomarkers for AKI will provide new tools to distinguish between the prerenal and established AKI. Achieving a consensus definition for prerenal syndrome will allow physicians to describe treatments and interventions as well as conduct and compare epidemiological studies in order to better describe the implications of this syndrome.