This article or section appears to contradict itselfon threshold for daily urine output qualifying as oliguria (variously given as 80-100mL/<400mL/<500mL in intro/Definition section). Please see the talk page for more information.(May 2021)
Beyond oliguria is anuria, which represents an absence of urine, clinically classified as below 80 or 100 ml/day.[1]
The term oliguria is derived from oligo-meaning "small, little," + -uria, from the Greek word ouron, meaning "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/kg/h. Alternatively, however, the value of 0.5 mL/kg/h is commonly used to define oliguria in adults as well.[4]
Diagnostic approach
Perform ultrasound examination of the kidney to rule out obstructive processes.[citation needed]
The mechanisms causing oliguria can be categorized globally in three different categories:[citation needed]
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:[citation needed]
fluid/ blood loss โ 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.[5]