Oliguria (Low Urine Output)

What is oliguria?

Oliguria is a medical term for low urine output (how much you pee). In the case of an adult, this means less than 400 milliliters (mL) to 500 mL (around two cups) of urine per 24 hours. The numbers depend on weight in terms of children and infants. For an infant, the output is less than 1 mL/kilogram (kg)/hour, while oliguria in children refers to an output of less than 0.5 mL/kg/hr.

What’s the difference between oliguria, anuria and polyuria?

These words and conditions are all related. They refer to how much urine you produce. The definition of oliguria is low urine output, while anuria means no urine output. Polyuria means excessive urine production.

Paying attention to urine has been a medical tool for thousands of years. Healthcare providers look at how much or how little you pee, what things are found in your pee (like blood or protein) and what color your pee is. Your healthcare provider, and you yourself, can learn important things by monitoring urine output and traits.

Who is affected by oliguria?

Low urine output can happen to anyone. It’s more likely to happen to people who have certain types of kidney diseases that can lead to acute kidney injury (AKI). AKI is also known as acute kidney failure.

Low urine output is somewhat common among people who are on dialysis or who are already in the hospital. People who are older may also be at more risk of developing oliguria.

How common is oliguria?

Low urine output is a common condition, partly because it can have so many different causes. It’s not always dangerous, but it certainly can be.

What causes oliguria?

Oliguria (low urine output) can be pre-renal (caused by something happening before the waste process gets to your kidneys), renal (caused by something in your kidneys) or post-renal (caused by something happening later in the waste removal process, not in your kidneys.)

Pre-renal causes include:

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

Renal causes include various types of kidney disorders, including glomerulonephritis and acute tubular necrosis, as well as damage due to medications or toxins.

Post-renal causes refer to blockages in your urinary tract, such as bladder outlet obstruction and ureteral stones. In cases of blockages, your kidneys make urine, but the urine can’t leave your body.

Is oliguria contagious?

No, oliguria isn’t contagious.

How is oliguria diagnosed?

Your healthcare provider will give you a physical exam and take a complete medical history. They’ll order tests that may include:

• Urine tests, including tests to measure urine and others to see what components are in it.
• Blood tests.
• Imaging tests, including ultrasound of your kidney or bladder and CT scans.

How is oliguria treated?

Oliguria treatment depends on the cause of low urine output.

If you aren’t able to excrete urine because something is blocked, your healthcare provider will remove the blockage so you can urinate (pee) normally. This is true for blockages in your urinary tract and from blockages that happen when a catheter is kinked or stopped up. (Catheters are tubes that are used to put fluid in your body or take fluid out.)

If you have an infection, you’ll get the correct antibiotics or antifungals.

If you’ve been taking a drug that has damaged your kidneys, your healthcare provider will stop that medication and replace it with another that isn’t toxic.

If your urine output is low because you’re dehydrated from vomiting or diarrhea, your healthcare provider will see to it that you’re rehydrated, either by drinking fluids or getting fluids intravenously (IV, through the vein).

People with kidney failure may need renal replacement therapy, like dialysis. Renal replacement therapy refers to treatment that performs the function of healthy kidneys.

Oliguria is likely to need medical treatment unless your urine output is low because you haven’t been taking in enough fluids. You may be able to treat yourself in that case by drinking more fluids, such as plain water or rehydration solutions that contain electrolytes.

Your healthcare provider might also suggest that you follow a diet that ensures you get a specific amount of protein and calories per day.

How can I prevent oliguria?

If you have diarrhea and are vomiting, make every effort to keep taking in fluids. It’s important to notice decreased urine production as early as you can.

If you have kidney disease, cardiac issues or breathing difficulties, follow your healthcare provider's directions as far as fluid intake and dietary guidelines.

What can I expect if I have oliguria?

In some cases, oliguria will go away with treatment, like when you’re dehydrated and then are able to take in enough fluid. Low urine output due to surgery or trauma should resolve somewhat quickly.

In cases where low urine production is related to kidney diseases or other conditions, the outlook depends on how well and how quickly the underlying condition is treated.

When should I see my healthcare provider about oliguria?

If you have cardiac or kidney issues, make sure you follow any directions your healthcare provider makes regarding medication, fluid intake and food choices. If you notice that you aren’t peeing as much as you usually do, try increasing your fluid intake and contact your healthcare provider. One sign that you aren’t drinking and peeing enough is that the color of your urine turns a darker yellow.

Get help right away if you have any worrying symptoms like fever, abdominal pain, extreme fatigue or confusion.