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
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/day (equals 17mL/hour) 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 hypovolemia and/or hypotension
- response of adrenal cortex to stress -increase in aldosterone (Na and water retention) and antidiuretic hormone (ADH) release
Oliguria in infants
Oliguria, when defined as less than 1 mL/kg/h, in infants
is not considered to be a reliable sign of renal failure.