and '''anuria''' are the decreased or absent production of
Urine , respectively. The decreased production of urine may be a sign of
Dehydration ,
Renal Failure or
Urinary Obstruction /
Urinary Retention .
Oliguria is defined as a urine output that is less than 1 mL/kg/h in infants, less than 0.5 mL/kg/h in children, and less than 400 mL/d in adults.
The pathophysiologic mechanisms causing oliguria can be categorized globally in three different categories:
Patients usually have decrease in urine output after a major operation that may be a normal physiological response to:
- fluid/ blood loss – decreased glomerular filtration rate secondary to hypovolumia and/or hypotension
- response of adrenal cortex to stress -increase in Aldosterone (Na and water retention) and Antidiuretic Hormone (ADH) release
