Nonoliguric acute renal failure.

Oliguria has been considered a cardinal feature of acute renal failure. However, many recent reports indicate that acute renal failure usually occurs in the setting of well-maintained urine output. Moreover, the nonoliguric state may accompany acute renal failure due to pre- and post-renal azotemia and a variety of renal parenchymal disorders, as well as acute tubular necrosis. Most studies indicate that nonoliguric forms of acute renal failure are associated with less morbidity and mortality than oliguric acute renal failure. Uncontrolled studies also suggest that volume expansion, potent diuretic agents, and renal vasodilators can convert oliguric to nonoliguric acute tubular necrosis if administered early in the course of acute renal failure. However, prospective studies of early intervention in oliguric patients are needed.