Oliguria occurs when you urinate less than 400 mL of urine per day. It’s usually a symptom of kidney problems, and may be caused by dehydration, injury, or some medications.

Most people without underlying health conditions or kidney problems have a normal daily urine output of 400 milliliters (mL), and will urinate at least once every 6 hours.

Oliguria is the medical term for a low urine output, and it’s one of the most common symptoms of acute kidney injury (AKI), previously known as acute kidney failure.

Keep reading to learn more about the potential causes of oliguria, other symptoms you may experience, and how it’s treated.

There are several guidelines and measurement cut-offs for defining oliguria.

Most experts define oliguria in the general population as urine volume measuring less than 400 mL per day, as established by the Kidney Disease Improving Global Outcomes (KDIGO) 2012 Guidelines.

To define oliguria in people with AKI, some experts use a threshold of 0.5 mL per kilogram of body weight per hour (mL/kg/h) over a specific time period. They may also use these measurements to classify the severity of oliguria:

  • Stage 1 (mild): Less than 0.5 mL/kg/h over 6 hours
  • Stage 2 (moderate): Less than 0.5 mL/kg/h over 12 hours
  • Stage 3 (severe): Less than 0.3 mL/kg/h over 24 hours

If you produce less than 50 to 100 mL of urine per day, you may have anuria, which is a serious medical emergency.

There are many potential causes of oliguria. These range from temporary conditions to more serious illnesses. Healthcare professionals sometimes classify the causes as pre-renal, renal, and post-renal.

Prerenal causes

Prerenal causes of oliguria reduce blood flow to the kidneys, thereby impairing their function. There are many pre-renal causes, some of which include:

Renal causes

Renal causes refer to blood-related complications, kidney diseases, or factors that directly impact kidney function. Some renal causes of oliguria include:

Post-renal causes

Post-renal causes are typically caused by urinary tract obstruction, which is when urine can’t leave your kidneys. This can affect one or both kidneys and usually results in decreased urine output.

Some causes of urinary tract obstruction may include:

There are many causes of oliguria, ranging from mild to severe. In many cases, oliguria is a sign of AKI, which may cause a wide range of symptoms, including:

It’s important to get immediate medical attention if you experience any of these symptoms along with lower urine output.

Consider speaking with a healthcare professional if you’re not peeing as much as usual, especially if you’re drinking plenty of water.

If you experience any other symptoms, such as dizziness, confusion, rapid pulse, or chest pain, get immediate medical attention. These may be signs of AKI or shock, which are life threatening conditions.

A healthcare professional will first perform a physical examination and ask you questions about your general health, any medications you’re taking, diet, and lifestyle habits.

They’ll also ask you questions about your urine patterns, such as when you started to experience low output, whether it occurred suddenly, and if it has worsened since it started.

It’s important to tell the doctor about how long you’ve experienced oliguria. Longer periods of low urine output are associated with more severe complications, such as AKI.

A doctor will also order several tests to assess your kidney function and urine output volume, and to identify the underlying cause of your symptoms.

Some tests may include:

Treatment will depend on the cause of your oliguria. It may take place in the hospital, with the aim of preventing AKI and supporting your kidney function.

The first step is to ensure you’re hemodynamically stable, which means a doctor will monitor your heart rate, blood pressure, blood oxygen levels, and hydration levels to ensure they’re stable.

This may require a doctor to administer an IV drip to quickly rehydrate your body or dialysis to help remove toxins until your kidneys can function correctly again. You may also need special drink mixes to replace any electrolytes lost during this time and prevent oliguria.

In severe cases, people may require a kidney transplant surgery to restore kidney function.

To manage oliguria and prevent it from recurring, a doctor may recommend:

  • stopping certain medications or alternating the dose
  • taking new medications, such as diuretics
  • adopting a specific diet

It’s essential to work closely with a healthcare professional, follow your treatment plan, and stay well hydrated. Oliguria may lead to serious complications if left untreated.

If left untreated, low urine output may lead to several complications that may require immediate medical attention and treatment. These may include:

Most cases require medical treatment. Consult a doctor as soon as you experience oliguria to develop a personalized treatment plan that works best for you.

Anuria is when your body does not produce any urine. Oliguria is when your body produces less urine. Polyuria is when your body produces too much urine.

Chances of dying from holding in pee are extremely low — some might even say nonexistent. The bladder can store up to 500 mL of urine in females and 700 mL in males, but your bladder will release involuntarily long before you’re in physical danger.

Unless there’s an underlying life threatening cause for low urine output, holding urine for a time will not cause immediate complications. However, holding it in for too long may cause damage to the bladder and infections.

Learn more: How Long Can You Go Without Peeing?

Oliguria means low urine output. Your kidneys can produce less urine for many reasons. Some causes are more serious than others. The most common cause is dehydration.

To avoid it, make sure to drink plenty of fluids. You may want to see a doctor for an evaluation to rule out other problems.