What Is Oliguria and Anuria?

Oliguria and anuria are signs that kidney function is declining or not up to the mark.

Oliguria and anuria are signs that kidney function is declining or not up to the mark.

Oliguria:

• Oliguria or hypouresis means not enough urine is produced by the kidneys. It is also called a low output of urine.
• It is clinically classified as a urine output of more than 80 mL/day but less than 400 mL/day.
• In infants and children, oliguria is defined as a urine output of less than 1 mL/kg/h and less than 0.5 mL/kg/h, respectively.
• Oliguria can be caused by any factor that affects renal (kidney) function or the free passage of urine down the urinary tract.
• Oliguria occurring commonly in hospitalized patients is usually secondary to impaired renal perfusion (reduced blood supply to the kidneys) and is often predictable. The elderly and more unwell patients, for example, those in critical care settings, are the most at risk. The presence of oliguria reflects the severity of the underlying disease processes.
• Common causes may include:
  • Dehydration: It occurs when more water and fluids leave the body than they enter it.
  • Hypovolemic shock: It is a life-threatening condition that results when people lose more than 20% (one-fifth) of their body's blood or fluid volume.
  • Hyperosmolar hyperglycemic nonketotic syndrome (HHNS): It is a potentially deadly condition that can develop as a result of infection or illness in patients with uncontrolled type 2 diabetes.
  • Diabetic ketoacidosis (DKA): It occurs when the blood sugar level is very high and acidic substances called ketones build up to dangerous levels in the body.
  • Pre-eclampsia: It is a pregnancy-related complication characterized by high blood pressure and signs of damage to another organ system, most often the liver and kidneys.
  • Urinary obstruction: Blockage can be complete or partial. Blockage can lead to kidney damage, kidney stones, and infection.
  • Urinary retention: Urinary retention is a condition in which the bladder doesn't empty and patients often feel like they have to urinate.
  • Urinary tract infection
  • Kidney failure
  • Multiple organ dysfunction

Anuria:

• Anuria represents an absence of urine. It is a more extreme reduction than oliguria (hypouresis).
• Anuria, sometimes called anuresis, is non-passage of urine; in practice, it is defined as the passage of less than 100 mL of urine in a day.
• It is often caused by a failure in the function of the kidneys.
• It most commonly occurs in men as a consequence of bladder outlet obstruction from an enlarged prostate.
• It can also occur in patients who have a single functioning kidney, which then becomes obstructed or loses its blood supply.
• It may also occur because of some severe obstruction such as kidney stones or tumors.
• It may occur with end-stage renal disease.