The Causes, Treatments, and Symptoms of Oliguria

The symptoms of oliguria are actually symptoms of an underlying condition. That's because oliguria in itself isn't a disease. Learn more in this article!

Reviewed and approved by the biologist Samuel Antonio Sánchez Amador.

Written by Samuel Antonio Sánchez Amador

Last update: 25 April, 2023

Chronic renal failure (CRF) is the progressive, permanent and irreversible loss of the kidneys’ glomerular filtration rate over a variable period of time. Oliguria is one of the symptoms of CRF, and today we’re going to tell you about the causes, treatments, and symptoms of oliguria.

According to epidemiological data, 17.8% of adults could suffer from this condition. However, that number increases to 45% in the elderly. Oliguria is generally defined as a decrease in urine output (diuresis). 

In addition to chronic kidney failure, it can also be a sign of acute kidney disease, dehydration, acute tubular necrosis, and many other etiologic agents.

Keep reading to find out more about this clinical condition.

What is oliguria?

A person who drinks 64 ounces of water a day should go to the bathroom, on average, every four hours to urinate. Their kidneys are continuously working to purify the blood, so our bodies produce about 27 to 68 ounces of urine a day.

According to the Navarra University Clinic, oliguria is the reduction of urinary volume below the necessary level. In general, experts say it’s a clinical issue when you’re only producing .01 ounces per minute, or less than 13.5 ounces every 24 hours. 
Of course, this cut-off point of 27 to 68 ounces of urine is for the “average” person. That means a person who weighs around 155 pounds, has normal blood pressure levels, and has optimal renal function. According to the MSDmanuals portal, experts classify oliguria into three different types:

1. Pre-renal: related to blood flow
2. Renal: caused by conditions intrinsic to the glomeruli and other kidney structures
3. Post-renal: obstruction in the structures where urine exits the body

Also, there’s a stage after oliguria called anuria. In this stage, there is no urine production at all. Doctors consider the condition to be anuria when the patient produces less than 3 ounces of urine in 24 hours. This is the most serious form of this condition. 

General terms

According to the parameters in the Electronic Journal of Medical Portals, and other information that experts have collected, these are the clinical stages when it comes to urinary conditions:

• Normal urine production: 27 to 68 ounces a day
• Oliguria: between 3 ounces and 13.5 ounces a day
• Anuria: less than 3 ounces a day
• Absolute anuria: no urine production. Unless proven otherwise, you should assume that your urinary tract is blocked.

The symptoms of oliguria

Like we previously mentioned, oliguria isn’t a disease in itself. Instead, it’s a clinical sign of another condition. The symptoms of oliguria can be very different and they depend on the underlying disease. Next, we’ll talk about the symptoms of acute kidney disease:

• Oliguria: decrease in volume of urine leaving the body, but it can remain stable in some cases.
• Lack of urination results in fluid retention which causes the legs, ankles, and feet to swell.
• Shortness of breath, fatigue, and disorientation.
• Nausea and weakness.
• Irregular heartbeat.
• Chest pain or tightness.
• Coma and unconsciousness in the most severe cases.

All of the symptoms indicate that something is wrong with your kidneys. When these organs don’t work well, toxic and harmful substances. In addition, it causes an imbalance in the blood composition. Also, the patient will lose their homeostatic balance.

Possible complications

If the kidneys don’t filter well, it can cause fluid to build up in the lung alveoli. This can make you feel overwhelmed, it can cause shortness of breath, or even death if the patient doesn’t act quickly.

In addition, because of the underlying processes, you may experience pericardium inflammation. This can cause chest pain or a change in your heart rate. Ultimately, all of these conditions could lead to death. Therefore, you must see a doctor if you notice any signs of kidney failure. 

The main causes of origuria

As we said, oliguria can be pre-renal, renal, or post-renal. Also, there are different causes of this condition, and those causes depend on the organs and structures that are being affected.

Dehydration

If there’s no fluid in the body, the kidneys can’t make urine. Prolonged diarrhea or repeated vomiting because of an infectious disease can cause your body to lose fluids and electrolytes. Therefore, oliguria is a clear sign of dehydration. 

Urinary tract obstruction

In this circumstance, you’re likely dealing with a post-renal etiologic agent. The MSD manuals portal states that the causes of urinary tract obstruction in adults are generally kidney stones, benign prostate hyperplasia, and, in the most severe cases, prostate cancer. 

Kidney disease

If your kidneys don’t filter blood properly, you may experience symptoms of oliguria. Chronic kidney disease, acute kidney disease (AKD), glomerulonephritis, or hemolytic uremic syndrome are clinical conditions that can drastically reduce urination rates.

Low cardiac output

Cardiac output is the amount of blood that the ventricle expels in one minute. If the heart doesn’t pump enough blood, the kidneys filter less and produce less urine. In addition, anemia, bleeding, and hypertension can cause pre-renal oliguria. 

Oliguria diagnosis

Oliguria isn’t a disease, so the diagnosis will be of the condition that’s causing it. First, the specialist will communicate with the patient. Then, if the patient has an urgent need to urinate, but can’t, the oliguria is probably the result of an obstruction in the urinary tract. 

On the other hand, if the patient is very thirsty, but doesn’t feel the need to go, they’re likely dehydrated. Also, a gradual decrease in the amount of urine the body produces over days (or months) may indicate acute tubular necrosis or a pre-renal cause.

After these initial distinctions, the doctor will decide which tests to carry out. In addition, it goes without saying that prostate cancer isn’t the same as reduced cardiac output due to hypertension. Each clinical condition will require a series of specific tests for diagnosis. 

When to see medical help for the symptoms of oliguria

Sometimes, it’s very normal to urinate less than normal. You may just not be hydrating enough during the workday. However, if that lack of urination is accompanied by any of the following symptoms, you should see a doctor:

1. You don’t urinate enough and your limbs are swollen.
2. You’re feeling tired and disoriented, and have trouble catching your breath.
3. You feel nausea and have pain/pressure in your chest.

Treatments

According to the previously cited medical portals, treatment will depend entirely on the cause of the oliguria. Before deciding on any medical treatment, the healthcare professional should ask the following questions:

1. Do you have normal blood pressure?
2. Is it possible you have kidney disease?
3. Is there any evidence of a urinary tract obstruction?

Based on those 3 questions and their answers, your doctor will suggest treatment options. Here are some of the most common approaches depending on the type of oliguria.

1. If the cause is pre-renal

If the oliguria is due to a dysfunction in blood pressure (and therefore cardiac output), it may be reversible. This will require proper treatment and early recognition of the condition. First, they’ll try intravenous fluid therapy, followed by the necessary drugs to stabilize the situation. 

2. If the cause is renal

According to the Kidney Foundation, the treatment for kidney issues will depend on what caused the issue in the first place. To stabilize the patient, the doctor may give hemodialysis and medications to control the number of vitamins and minerals in the blood. In addition, they may use drugs that will stabilize the volume of fluids in the body.

3. If the cause is post-renal

If the cause of the urinary tract obstruction is kidney stones, the doctor will usually try shock wave lithotripsy. These waves will break the sediment into small pieces so that the patient can get rid of them more easily. As a result, this will remove the “plug” that was keeping the urine from getting out.

The symptoms of oliguria are actually symptoms of an underlying condition

In conclusion, oliguria isn’t a disease in itself, but rather a clinical condition. It’s a sign that you’re experiencing failure at the vascular, renal, or urinary tract level. 

Also, treatment will depend entirely on the underlying cause. That’s because you’re not going to treat a kidney injury the same way you would treat prostate cancer. So, if you’ve noticed a decrease in your urine levels, we recommend seeing a doctor.