[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".
[4] 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] Patients usually have a decrease in urine output after a major operation that may be a normal physiological response to:[citation needed] Oliguria, when defined as less than 1 mL/kg/h, in infants is not attributed to kidney failure.