| Oliguria | |
| Synonyms: | Hypouresis |
| Field: | Urology |
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, 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.[1]
The term oliguria is derived from oligo-meaning "small, little," + -uria, from the Greek word ouron, meaning "urine".[2]
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]
Perform ultrasound examination of the kidney to rule out obstructive processes.
The mechanisms causing oliguria can be categorized globally in three different categories:
Patients usually have a decrease in urine output after a major operation that may be a normal physiological response to:
Oliguria, when defined as less than 1 mL/kg/h, in infants is not attributed to kidney failure.[5]