Oliguria

Oliguria or hypouresis is the low output of urine specifically more than 80 ml/day but less than 400ml/day.[1] The decreased output of urine may be a sign of dehydration, kidney failure, hypovolemic shock, HHNS hyperosmolar Hyperglycemic Nonketotic Syndrome, multiple organ dysfunction syndrome, urinary obstruction/urinary retention, DKA, pre-eclampsia, and urinary tract infections, among other conditions.

Oliguria
Other namesHypouresis
SpecialtyUrology

Beyond oliguria is anuria, which represents an absence of urine, clinically classified as below 80 or 100 ml/day.[1] The term is from roots meaning "not enough urine").[2]

Definition

Oliguria is defined as a urine output that is less than 1 mL/kg/h in infants,[3] less than 0.5 mL/kg/h in children,[3] and less than 400 mL[3] or 500 mL[4] per 24h in adults - this equals 17 or 21 mL/hour. For example, in an adult weighing 70 kg 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.[4]

Olig- (or oligo-) is a Greek prefix meaning small or few.[5]

Anuria is clinically defined as less than 100mL urine output per day.

Diagnostic approach

Perform ultrasound examination of the kidney to rule out obstructive processes.

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

Postoperative oliguria

Patients usually have a 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

Babies

Oliguria, when defined as less than 1 mL/kg/h, in infants is not attributed to kidney failure [6].

See also
  • Polyuria (excessive urine production)
  • Anuria (absolute lack of urine output)
  • Intraabdonmial hypertension (IAH) and Abdominal Compartment Syndrome (ACS)

References
  1. Boon et al, Davidson's Principles & Practice of Medicine (20th Ed), p475
  2. "oliguria" at Dorland's Medical Dictionary
  3. Klahr S, Miller S (1998). "Acute oliguria". N Engl J Med. 338 (10): 671–5. doi:10.1056/NEJM199803053381007. PMID 9486997. Free Full Text.
  4. Merck manuals > Oliguria Last full review/revision March 2009 by Soumitra R. Eachempati
  5. "Archived copy". Archived from the original on 2008-09-14. Retrieved 2009-01-19.CS1 maint: archived copy as title (link)
  6. 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.
Classification
External resources
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