Oliguria or hypouresis (both names from roots meaning “not enough urine”) is the low output of urine. In humans, it is clinically classified as an output 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, HHNS hyperosmolar Hyperglycemic Nonketotic Syndrome, multiple organ dysfunction syndrome, urinary obstruction/urinary retention, 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.
Anuria, sometimes called anuresis, is nonpassage of urine, in practice is defined as passage of less than 50 milliliters of urine in a day. Anuria is often caused by failure in the function of kidneys. It may also occur because of some severe obstruction like kidney stones or tumours. It may occur with end stage renal disease. It is a more extreme reduction than oliguria (hypouresis), with 100 mL/day being the conventional (albeit slightly arbitrary) cutoff point between the two.
Are there any risks associated with oliguria?
If you fail to get yourself diagnosed in the right time, then you can develop health disorders like:
- Acute renal disorder
- Heart failure
- High blood pressure
- Gastrointestinal problems
Symptoms of anuria:
- The only symptom of anuria is decreased output of urine. Quantity of urine can get reduced gradually and in some cases dribbling of urine can be taken as a sign of anuria. Excess of fluid loss, diarrhea or excess of vomiting are some other symptoms of anuria.
- Changes in voiding behavior can be taken as a sign of anuria. If you observe you are not passing normal amount of urine without any obvious causes it can be anuria. One can check the amount of fluid taken in 24 hours and the amount expelled from the body by measurements.
Causes of anuria include:
- Diabetes: Uncontrolled diabetes can lead to diabetic ketoacidosis, which in turn can lead to anuria from acute kidney failure.
- High blood pressure (hypertension): Over time this can damage the arteries surrounding your kidneys, disrupting kidney function.
- Kidney failure: This condition occurs when your kidneys can no longer provide key functions, including urine output.
- Chronic kidney disease: A form of long-term kidney failure, this condition decreases your body’s ability to remove waste through your urine.
- Kidney stones: Made from excess levels of minerals from your urine, kidney stones can get large and obstruct urine output, causing pain and other complications.
- Tumors in your kidneys: Not only can tumors interfere with kidney function, but they can also obstruct the urination process.
How is anuria diagnosed?
To diagnose anuria, your doctor will first ask you about your symptoms. They might ask about:
- fluid retention
- recent trouble urinating
- decreased visits to the bathroom
- blood in your urine
Certain tests may also help diagnose anuria. These primarily look at the overall condition of your kidneys. Options include:
- a biopsy of a small sample of kidney tissue
- blood tests to look for excess waste
- a CT scan, which uses X-rays (This test may focus on either your urinary tract only or your entire body.)
- an MRI scan to take pictures of your kidneys by using radio frequencies
- renal scintigraphy, which tests the function of your kidneys via nuclear medicine
- urine tests
Can anuria cause complications?
Not treating anuria can lead to life-threatening complications. Untreated anuria ultimately means that the underlying condition isn’t being treated either.
Anuria can lead to permanent kidney damage, which can be fatal. The risk is greater in cases of acute kidney failure.
How to treat anuria?
Anuria is considered a medical emergency requiring medical intervention right away. But in a hospital setting, the most common cause is not something serious, but in fact, it’s usually just a fold or kink in the catheter line, so it is always important to make sure this is not the case before proceeding to more invasive intervention.
It is best to avoid self-diagnosis of anuria and to allow a doctor to make their final assessment, as they can provide suitable and effective treatment. Some cases may require surgical intervention, while less severe cases only require the use of antibiotic medication. Stopping any medication that is known to damage the kidneys is also recommended.
The cause of anuria—prerenal, renal, or postrenal—will often dictate what is needed to be done to resolve it. Supportive treatment is often done in conjunction with medical intervention and may involve the use of fluids, diuretic medication, and close monitoring of blood metabolites.