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Blood Urea Nitrogen (BUN) Test

A blood urea nitrogen (BUN) test analyses the amount of urea in a sample of blood. Urea is a waste product that forms as a part of the body’s natural process of breaking down proteins. This is also referred to as urea nitrogen and is filtered out of the blood by the kidneys.

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What is a  Blood Urea Nitrogen (BUN) test? 

A blood urea nitrogen (BUN) test is used to evaluate how well your kidneys are functioning. It does so by analysing the amount of urea nitrogen in the blood. Urea nitrogen is a waste product that is created by the liver when the body breaks down the proteins. Normally, the kidneys filter out the waste and urinating removes it from the body. BUN levels tend to increase when the kidneys or liver are damaged or malfunctioning. And having too much urea nitrogen in the bloodstream can be a sign of kidney or liver problems.


What are the other names for the Blood Urea Nitrogen (BUN) test? 

The other names are Urea nitrogen test and serum BUN. 

What are the test parameters included in the Blood Urea Nitrogen (BUN) test?

There is only one parameter: blood urea nitrogen.

What does a Blood Urea Nitrogen (BUN) test measure?

Blood Urea Nitrogen test analyses the amount of urea nitrogen in the blood. This urea is a waste product that is formed in the liver. It is formed when the protein is metabolised into the amino acids. It leads to the production of ammonia, which is further converted into urea. There is a less toxic waste product. 


Usually, both ammonia and urea have nitrogen as the main component. The liver releases urea into the blood, which is then carried to the kidneys. Here, it is filtered out of the blood and then it is released into the urine. This is a continuous process, a small amount of urea nitrogen always remains in the blood.


In the case of kidney or liver disease, there will be a change in the amount of urea present in the blood. If the liver produces urea in increased amounts or in case there is any problem in the functioning of the kidneys, there may be difficulty in filtering out the waste products from the blood, which will lead to a rise in urea concentrations in the blood. If it is due to liver damage or disease, there is less production of urea, and the concentration of BUN will fall.


The BUN test is done along with a creatinine test to evaluate kidney function, diagnose kidney disease, and monitor patients undergoing treatment for kidney disease. 


What’s the normal range? 

7-20 mg/dL

Who should get a Blood Urea Nitrogen (BUN) test? 

Blood urea nitrogen (BUN) is most commonly analysed as a part of the basic or comprehensive metabolic panel. These tests may involve 8 and 14 measurements, respectively, and they provide insight into the multiple bodily systems, including the kidney function.


A panel of these tests with a BUN measurement included may be appropriate if you have any symptoms of kidney disease. In addition, these test panels with BUN may be used to help with a diagnosis when you have general symptoms or are being evaluated in an emergency room or an urgent care centre. Your physician may recommend screening these tests, including a BUN measurement, if you have any risk factors for kidney disease, such as a family history of kidney problems or related issues, diabetes, or cardiovascular issues like high blood pressure.

The doctor might also order the screening tests with a BUN measurement during routine medical exams.

If you have previously had an abnormal BUN test report or you have a known kidney problem, repeat testing at regular intervals might be appropriate in order to monitor your situation and current kidney function.


Are Preparations Needed for the Blood Urea Nitrogen (BUN) Test?

There is no preparation for this test. Fasting is not required.

What is the cost of a BUN test?

What is the type of sample required? 

This test requires a blood sample.

Who performs a Blood Urea Nitrogen (BUN) test?

A healthcare provider, who is also called a phlebotomist, usually performs blood draws, including those for blood urea nitrogen tests, but any healthcare provider trained in drawing blood can perform this task. Usually, the samples are sent to a lab where a medical laboratory scientist prepares the samples and performs the tests on analysers or manually.

What should I expect during my Blood Urea Nitrogen (BUN) test?

You can expect the experience the following during the blood test or a blood draw:

  • You will have to sit comfortably on the chair, and a healthcare provider will check your arms for an easily accessible vein. This is the inner part of your arm on the other side of your elbow.

  • Once they have located a vein, they will clean and disinfect the area with an alcohol swab.

  • Then they will insert a small needle into your vein to draw a blood sample. This might feel like a small pinch.

  • After they have inserted the needle, the required amount of blood will collect in a test tube.

  • When they have collected enough blood for the test, they’ll remove the needle and hold a cotton ball or gauze on the site to stop any bleeding.

  • They will put a band-aid over the pricked site, and the blood collection is finished.

This process takes less than five minutes.

What should I expect after my Blood Urea Nitrogen (BUN) test?

After a healthcare provider has collected the blood sample, it will be sent to the laboratory for processing or testing. When the results are ready, your healthcare provider will share the results with you.

What are the risks of a Blood Urea Nitrogen (BUN) test?

These blood tests are very common and don’t carry any significant risks. You may have a  slight pain like an ant bite when the needle gets inserted, and a small bruise may develop there.

When can I expect my Blood Urea Nitrogen (BUN) test results?

These reports are available via email or WhatsApp within 6 hours of the collection of the blood sample.

What do the results of a Blood Urea Nitrogen (BUN) test mean? 

Interpreting test results

The test report shall include a line for blood urea nitrogen that shows the values found in your sample as well as the laboratory’s reference range. BUN is analysed in milligrams per deciliter of blood (mg/dL).

Working with the doctor is the best way to understand the clinical significance of the BUN test. The American Board for Internal Medicine lists the typical reference range for blood urea nitrogen as 7 to 20 mg/dL. However, this range is not universal. Laboratories can use different methodologies to measure BUN, and what constitutes a normal result can vary from lab to lab.

If you have added a panel test, you should see the separate test results for any other measurements taken along with blood urea nitrogen. Each of the test components will have the listed reference range for the laboratory where they have conducted your test.


The doctor can discuss your BUN test levels and how they relate to your overall health conditions, any symptoms you may have, and other test measurements. This is very important because BUN levels alone can not be a consistent predictor of kidney function. The elevated BUN test can occur with kidney problems, but it can also happen when you are eating lots of protein, taking certain medications, or from other issues like dehydration or burns. These BUN levels often rise with ageing as well.


Blood urea nitrogen may not reflect kidney function independently. For this reason, it is often interpreted in the context of other measurements such as creatinine, a breakdown product of the muscle that is filtered by the kidneys. In some cases, the doctor might look at the ratio of BUN to creatinine to help evaluate the underlying cause of the altered kidney functions.


And abnormally low levels of BUN can be a sign of malnutrition, lack of protein in the diet, and liver disease. Therefore, other tests also included in a panel test like the comprehensive metabolic panel may provide helpful information for understanding the significance of low blood urea nitrogen.


What are normal Blood Urea Nitrogen (BUN) test results?

7-20 mg/dL

What other tests might I have along with this test?

Serum Creatinine.

How do I book a Blood Urea Nitrogen (BUN) test at home?

Log on to and submit your details. Our highly trained, professional, and vaccinated eMedics will be at your doorstep within 60 minutes or at the time booked by you.


FAQs on BUN Test

What is blood urea nitrogen in a blood test?

A blood test, the blood urea nitrogen (BUN) test, reveals important information about how well your kidneys are working. A blood urea nitrogen test analyses the amount of urea nitrogen that is in your blood.

What happens if urea is high in the blood?

Normal blood urea nitrogen levels vary, but high levels in your blood sample usually mean your kidneys are not working normally. They may be a sign of kidney disease or failure. Higher than normal blood urea nitrogen values can also indicate dehydration, a high protein diet, medications, burns, or other conditions.

What does a high urea nitrogen count mean?

A high blood urea nitrogen value means your kidneys are not working properly. But increased blood urea nitrogen may also be due to dehydration resulting from not drinking enough fluids or for other reasons, urinary tract obstruction, congestive heart failure, or any recent heart attack. 


What level of BUN indicates kidney failure?

A glomerular filtration rate (GFR) is a sign that the kidneys are not working properly. Once the GFR decreases below 15, one is at a high risk of needing treatment for kidney failures, such as dialysis or a kidney transplant. Blood urea nitrogen comes from the breakdown of protein in the foods we eat. A normal BUN value is between 7 - 20 mg/dL.

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