Oliguria or hypouresis is the low output of urine specifically more than 80 ml/day but less than 400ml/day. 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. The term oliguria is derived from oligo-meaning "small, little," + -uria, from the Greek word ouron, meaning "urine"..