Oliguria

From Wikipedia, the free encyclopedia

Name of Symptom/Sign:
**Oliguria**
*Classifications and external resources*
ICD-10	R34
ICD-9	788.5

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.

1 Definition
2 Pathophysiology
- 2.1 Postoperative oliguria
3 Oliguria in infants
4 References

[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 300 mL/day in adults.<ref>Klahr S, Miller S (1998). "Acute oliguria.". N Engl J Med 338 (10): 671-5. PMID 9486997. Free Full Text.</ref>

[edit] Pathophysiology

The pathophysiologic mechanisms causing oliguria can be categorized globally in three different categories:

Prerenal: in response to hypoperfusion of the kidney (e.g. as a result of dehydration by poor oral intake, diarrhea, massive bleeding or sepsis)
Renal: due to kidney damage (severe hypoperfusion, rhabdomyolysis, medication)
Postrenal: as a consequence of obstruction of the urine flow (e.g. enlarged prostate, tumour compression urinary outflow, expanding hematoma or fluid collection)

[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.<ref>Arant B (1987). "Postnatal development of renal function during the first year of life.". Pediatr Nephrol 1 (3): 308-13. PMID 3153294.</ref>