Oliguria

Template:Short description {{ safesubst:#invoke:Unsubst||date=__DATE__ |$B= Template:Ambox }}Template:Infobox medical condition (new) Oliguria or hypouresis is the low output of urine specifically more than 80 ml/day but less than 400ml/day.<ref name="Boon p475">Template:Cite book</ref> The decreased output of urine may be a sign of dehydration, kidney failure, hypovolemic shock, hyperosmolar hyperglycemic nonketotic syndrome (HHNS), multiple organ dysfunction syndrome, urinary obstruction/urinary retention, diabetic ketoacidosis (DKA), pre-eclampsia, and urinary tract infections, among other conditions.

Beyond oliguria is anuria, which represents an absence of urine, clinically classified as below 80 or 100 ml/day.<ref name="Boon p475"/>

The term oliguria is derived from oligo-meaning "small, little," + -uria, from the Greek word ouron, meaning "urine".<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Definition

Oliguria is defined as a urine output that is less than 1 mL/kg/h in infants,<ref name=klahr>Template:Cite journal Free Full Text.</ref> less than 0.5 mL/kg/h in children,<ref name=klahr/> and less than 400 mL<ref name=klahr/> or 500 mL<ref name=merck>Merck manuals > Oliguria Last full review/revision March 2009 by Soumitra R. Eachempati</ref> 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/kg/h. Alternatively, however, the value of 0.5 mL/kg/h is commonly used to define oliguria in adults as well.<ref name=merck/>

Diagnostic approach

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

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

• Prerenal: in response to hypoperfusion of the kidney (e.g. as a result of dehydration by poor oral intake, cardiogenic shock, diarrhea, G6PD deficiency, 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)

Postoperative oliguria

Patients usually have a decrease in urine output after a major operation that may be a normal physiological response to:Template:Cn

• 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.<ref>Template:Cite journal</ref>

See also

• Polyuria (excessive urine production)
• Anuria (absolute lack of urine output)
• Intra-abdominal hypertension (IAH) and Abdominal Compartment Syndrome (ACS)