Oliguria
| ICD-10 | R34 |
|---|---|
| ICD-9 | 788.5 |
| MeSH | D009846 |
Oliguria is the low output of urine,[1] It is clinically classified as an output below 300-500ml/day[2]. The decreased output of urine may be a sign of dehydration, renal failure, hypovolemic shock, HHNS Hyperosmolar Hyperglycemic Nonketotic Syndrome, multiple organ dysfunction syndrome, urinary obstruction/urinary retention, and Urinary tract infections.
It can be contrasted with anuria, which represents an absence of urine, clinically classified as below 50ml/day[3].
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[edit] Definition
Oliguria is defined as a urine output that is less than 1 mL/kg/h in infants,[4] less than 0.5 mL/kg/h in children,[4] and less than 400 mL[4] or 500 mL[5] per 24h in adults - this equals 17 or 21 mL/hour. For example, in an adult weighing 70kg it equals 0.24 or 0.3 ml/hour/kg. Alternatively, however, the value of 0.5 mL/kg/h is commonly used to define oliguria in adults as well.[5]
Olig- (or oligo-) is a Greek prefix meaning small or few.[6]
Anuria is defined as less than 50mL urine output per day.
[edit] Testing
Perform ultrasound examination of the kidney to rule out obstructive processes.
[edit] Pathophysiology
The pathophysiologic mechanisms causing oliguria can be categorized globally in three different categories[7]:
- Prerenal: in response to hypoperfusion of the kidney (e.g. as a result of dehydration by poor oral intake, cardiogenic shock, 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.[8]
[edit] References
- ^ "oliguria" at Dorland's Medical Dictionary
- ^ Boon et al, Davidson's Principles & Practice of Medicine (20th Ed), p475
- ^ Boon et al, Davidson's Principles & Practice of Medicine (20th Ed), p475
- ^ a b c Klahr S, Miller S (1998). "Acute oliguria". N Engl J Med 338 (10): 671–5. doi:10.1056/NEJM199803053381007. PMID 9486997. Free Full Text.
- ^ a b Merck manuals > Oliguria Last full review/revision March 2009 by Soumitra R. Eachempati
- ^ http://biology.about.com/od/prefixesandsuffixeso/g/blo3.htm
- ^ http://beavermedic.wordpress.com/2010/01/19/the-kidneys/
- ^ 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.
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