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Oliguria 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.
[edit] Definition
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.[1]
[edit] Pathophysiology
The pathophysiologic mechanisms causing oliguria can be categorized globally in three different categories:
[edit] Postoperative oliguria
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
[edit] 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.[2]
[edit] References
- ^ Klahr S, Miller S (1998). "Acute oliguria.". N Engl J Med 338 (10): 671-5. doi:10.1056/NEJM199803053381007. PMID 9486997. Free Full Text.
- ^ Arant B (1987). "Postnatal development of renal function during the first year of life.". Pediatr Nephrol 1 (3): 308-13. doi:10.1007/BF00849229. PMID 3153294.
