Formerly, acute kidney injury (AKI) used to be called acute renal failure or insufficiency. Amid the most common causes of acute renal failure is prerenal azotemia, which appears when renal perfusion is inadequate, leading to a transient elevation of serum creatinine level. This may be as a result of decreased intravascular volume which caused by relative dehydration or blood. It also can result from low effective arterial volume even if the individual is fluid overloaded, in the setting of heart failure or liver disease. In recent past, AKI has been considered any transient elevation in serum creatinine. There is an impulse to avoid fluid administration for AKI and to initiate dialysis therapy prior to remove fluid. Available studies have implied to start dialysis earlier and remove more fluid even before creatinine is elevated. Not rarely, other specialists, particularly cardiologists, and cardiothoracic surgeons, want more fluid to be removed as chest X-rays look clear. Loop diuretics generally are feeble, so dialysis therapy with large amounts of ultrafiltration is desired, no matter how adverse these aspects are to the injured kidneys.