Oliguria

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Oliguria
ICD-10 R34
ICD-9 788.5
MedlinePlus 003147
MeSH D009846

Oliguria or hypouresis (both names from roots meaning "not enough urine") is the low output of urine.[1] In humans, it is clinically classified as an output more than 100 ml/day but less than 400ml/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, DKA, pre-eclampsia, and urinary tract infections, among other conditions.

The most extreme type of Oliguria is called anuria, which represents an absence of urine, clinically classified as below 50ml/day.[2]

Definition[edit]

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 defined as less than 50mL urine output per day.

Testing[edit]

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

Pathophysiology[edit]

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

Postoperative oliguria[edit]

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[edit]

Oliguria, when defined as less than 1 mL/kg/h, in infants is not considered to be a reliable sign of renal failure.[6]

References[edit]

  1. ^ "oliguria" at Dorland's Medical Dictionary
  2. ^ a b Boon et al, Davidson's Principles & Practice of Medicine (20th Ed), p475
  3. ^ 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.
  4. ^ a b Merck manuals > Oliguria Last full review/revision March 2009 by Soumitra R. Eachempati
  5. ^ http://biology.about.com/od/prefixesandsuffixeso/g/blo3.htm
  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.