What is the Blood Urea Nitrogen test?

Frequently Asked Questions:

What is the Blood Urea Nitrogen test used for?

The Blood Urea Nitrogen (BUN) test is used to study the levels of the waste product in your blood. This test helps in the diagnosis and monitoring of kidney disorders in case the kidneys aren’t functioning properly. The BUN test can detect any kidney issues at an early stage, which helps in getting timely treatment.

Understanding the test results of the Blood Urea Nitrogen test.

Normal BUN levels fall between 7 and 20 milligrams per deciliter. 

High levels of Blood Urea Nitrogen (BUN) in the blood are an indication of incorrect functioning of the kidneys. However, high or low BUN levels may also be due to dehydration, a high protein diet, burns, gastrointestinal bleeding, or a recent heart attack.  BUN levels also increase due to certain medications and ageing.

Why do I need the Blood Urea Nitrogen test?

You require a Blood Urea Nitrogen test in case of a kidney disorder, or if you suffer from diabetes, high blood pressure, heart disease, or have a family history of kidney disease. You will also need this test if you show symptoms, such as:

• Change in frequency of urination
• Discoloured urine
• Pain during urination
• Pain in the back where kidneys are located

What happens during the Blood Urea Nitrogen test?

During the BUN test, a lab technician cleans the puncture spot in the middle of your arm with antiseptic. Then they insert a needle into your vein to take the blood sample, which is collected into a vial. You will feel a slight prick of the needle, but the pain will go away quickly.

What causes high BUN levels?

The inability of the kidneys to remove the waste products efficiently causes high BUN levels. Other factors, such as a high protein diet, dehydration, heart failure, gastrointestinal bleeding, stress, pregnancy, and ageing, can cause high BUN levels. Certain medications, such as steroids and antibiotics, also cause the BUN levels to rise.

What level of BUN indicates kidney failure?

Blood urea nitrogen (BUN) is measured to diagnose kidney function. A higher than normal BUN level indicates a decline in kidney function due to kidney disease or disorder. There is no definite BUN value that indicates kidney failure. Specific tests, such as glomerular filtration rate (GFR) and creatinine clearance, help diagnose kidney failure.

What does blood urea nitrogen tell you?

Blood urea nitrogen tells you how well your kidneys are functioning. It shows the level of urea nitrogen in your blood. If the kidneys aren’t able to remove the urea nitrogen, it means they aren’t functioning normally. The blood urea nitrogen helps in the early detection of a kidney disorder and planning appropriate treatment. 

What are the symptoms of high BUN levels?

The BUN test helps detect the levels of blood urea nitrogen, study the functioning of the kidneys, and diagnose kidney disease. The symptoms of high BUN levels are:

• Frequent urination
• Discoloured or bloody urine
• Fatigue
• Muscle cramping
• Joint pain and back pain
• Loss of appetite
• Itchiness
• Swelling in hands and feet
• Restless legs

How do I prepare for the test?

Before taking the BUN test, it is important to inform the doctor about any medications you take, such as steroids or antibiotics, as those medications could alter the test results. You may be asked to stop taking those medications for some time. If you are taking just the BUN test, you may not need to fast.

Are there any risks associated with the test?

There are very few risks associated with the BUN test. There will be bruising at the puncture site, an accumulation of blood, or infection. If you have a bleeding disorder, or you are taking blood thinners, it may cause you to bleed more during the test. In either case, please seek your doctor’s advice. 

Please visit Yashoda Hospitals for a free second opinion or more information on the management and care of kidney disease.