Oliguria (Low Urine Output)

Oliguria (pronounced al-uh-GYOOR-ee-uh) is a medical term for low urine output (how much you pee). “Oliguria” is a big word. Breaking it apart can help you understand the meaning:

• Oligo-. This comes from the Greek word “oligos,” which means “few” or “little.”
• -uria. This comes from the Greek word “ouria,” which means “to urinate.”

In adults, oliguria means you pee less than 400 milliliters (mL) to 500 mL (around two cups) of pee per 24 hours.

For infants and children, the numbers depend on weight. For an infant, the output is less than 1 mL/kilogram (kg)/hour. For children, the output is less than 0.5 mL/kg/hour.

Low urine output is relatively common because it can have so many causes. It’s not always dangerous. But it can be, depending on the cause.

Types of oliguria

Healthcare providers may classify oliguria according to how long it takes to develop:

• Acute oliguria. This type develops suddenly.
• Chronic oliguria. This type takes longer to develop. Chronic oliguria is more likely to occur if you’re on long-term dialysis.

Symptoms of oliguria

The primary symptom of oliguria is that you’re not peeing as much as you should be. Other symptoms depend on the underlying cause. They may include:

• Abdominal pain
• Cold hands and feet
• Flank pain
• Heart rate that’s faster than normal (tachycardia)
• High acid levels in your blood (metabolic acidosis)
• High potassium levels in your blood (hyperkalemia)
• High waste levels in your blood (uremia)
• Low blood pressure (hypotension)
• Swelling (edema)

What causes oliguria?

Oliguria can be:

• Pre-renal. This means something happens in your urinary system before the waste process gets to your kidneys.
• Renal. There’s something affecting your kidneys. “Renal” means it relates to the kidneys.
• Post-renal. Something happens later in the waste removal process, after your kidneys filter your blood.

Pre-renal causes

Pre-renal causes may include:

• Heart and lung conditions
• Low blood volume (hypovolemia), which can be caused by heavy blood loss, decreased fluid intake, burns, sepsis, liver failure and surgery
• Vascular disease of your kidneys

Renal causes

Renal causes may include:

• Kidney damage due to medications or toxins
• Kidney disorders, including glomerulonephritis and acute tubular necrosis

Post-renal causes

Post-renal causes refer to blockages in your urinary system, such as a:

• Bladder outlet obstruction
• Ureteral stone

If you have a blockage, your kidneys still make pee, but the pee can’t leave your body.

Is oliguria dehydration?

Not always. But a low urine output can result from not drinking enough fluids (dehydration).

Risk factors

Low urine output can happen to anyone. But it’s more likely to happen if you have certain types of kidney diseases that can lead to acute kidney injury (AKI).

Low urine output is somewhat common among people who are on dialysis or who are already in the hospital. You may also be at a greater risk of developing oliguria if you’re 50 or older.

What happens if you don’t pee enough?

One of the most common complications in acute oliguria is that your kidneys suddenly can’t do a good job filtering toxins or wastes from your blood. This can lead to acute kidney failure. Potentially deadly complications of acute kidney failure include:

• Electrolyte imbalances, including high levels of potassium (hyperkalemia) and acids (metabolic acidosis)
• Neurological disorders, including overactive reflexes in your muscles (hyperreflexia), seizures and coma
• Problems with the organs in your digestive system, including gastrointestinal bleeding and inflammation in your stomach lining (gastritis)
• Problems with your heart and blood vessels, including an abnormal heartbeat (arrhythmia), congestive heart failure and high blood pressure
• Problems with your lungs, including abnormal breathing patterns (Kussmaul breathing)

How doctors diagnose oliguria

A healthcare provider will take a complete medical history and perform a physical exam. They may also recommend tests such as:

• Blood tests
• Imaging tests, including CT scans and an ultrasound of your kidney or urinary bladder
• Urine tests (urinalysis), including tests to measure how much you pee and what components are in it

How do you fix oliguria?

Oliguria treatment depends on the cause of low urine output:

• If you can’t pee much because there’s a blockage, a healthcare provider will remove the blockage. This is true for blockages in your urinary system and blockages that happen when there’s a kink in a urinary catheter.
• If you have an infection, you’ll get the correct antibiotics or antifungals.
• If a medication has damaged your kidneys, a provider will stop that medication and replace it with another, if necessary.
• If your urine output is low because vomiting or diarrhea causes dehydration, a provider will help you rehydrate by helping you drink fluids or intravenous (IV) fluids.
• If you have kidney failure, you may need dialysis.
• A provider may also recommend that you eat foods that provide the right amount of protein and calories for your condition.

Should I drink water if I can’t pee?

It depends on the cause. You should drink fluids if your urine output is low because you haven’t been taking in enough fluids. Plain water and rehydration solutions that contain electrolytes are good options. Some rehydration options include:

• Clear broth
• Diluted juices
• Sports drinks

When should I see my healthcare provider?

If you have issues with your heart or kidneys, make sure you follow any directions a healthcare provider makes regarding medications, fluid intake and food choices. If you notice you aren’t peeing as much as you usually do, try increasing your fluid intake and contact a provider. One sign of dehydration and reduced urine output is that the color of your pee turns a darker yellow.

You may wish to ask a provider questions such as:

• What’s affecting my urine output?
• Is it serious?
• Do I have severe symptoms?
• What treatment do you recommend?
• Should I look out for any signs of complications?
• Do I need to adjust what I eat and drink?
• Should I see a dietitian?

Get help right away if you aren’t peeing as much as you think you should be and you have symptoms like:

• Abdominal pain
• Confusion
• Feeling very tired (fatigue)
• Fever

How can oliguria be prevented?

If you have diarrhea or are vomiting, make every effort to keep taking in fluids. It’s important to note low urine output as early as you can.

If you have problems breathing or issues with your kidneys or heart, follow a healthcare provider’s directions as far as how much you should drink each day and what you should eat.

What can I expect if I have oliguria?

Your outlook depends on what’s affecting your urine output. But if you’re not peeing as much as you should be, that’s your body’s way of telling you that something is wrong, and you should reach out to a healthcare provider right away. Without treatment, serious complications can develop.