BUN Test

1 What is a Blood Urea Nitrogen (BUN) Test?

The blood urea nitrogen test is a common blood test that reveals vital information about how your kidney and liver are working. A BUN test measures the amount of urea nitrogen in your blood.

Your liver produces ammonia, which contains nitrogen after breaking down protein used by your body.

The nitrogen combines with other elements, such as carbon, hydrogen, and oxygen, to form urea, which is a chemical waste product.

The urea then moves from your liver to your kidneys via your bloodstream. Healthy kidneys remove urea and other waste products from the blood.

A BUN test can reveal whether your urea nitrogen levels are higher than they should be, suggesting that your liver or kidneys may be malfunctioning.

2 Reasons for Procedure

You may need a blood urea nitrogen test for the following reasons:

If your doctor has a suspicion of kidney or liver damage. If your kidney function has to be evaluated.

To help detect the effectiveness of dialysis treatment of your are using hemodialysis or peritoneal dialysis.

As part of a group of a blood test to help diagnose various conditions, such as liver damage, urinary tract obstruction, congestive heart failure or gastrointestinal bleeding.

If kidney problems are the main complications, when your blood is tested for urea nitrogen levels, it is also likely to b tested for creatine levels as well.

Creatine is a waste product that healthy kidneys filter out of your body through urine. High levels of creatine may be a sign of kidney damage.

In order to get the best indication of how efficient your kidneys are removing wastes from the blood, you may have a blood sample taken to calculate your estimated glomerular filtration rate ( eGFR).

The eGFR estimates the percentage of kidney function you have left.

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3 Potential Risks

A blood urea nitrogen test is generally a safe procedure, with no potential risks, it only involves a taking a sample of blood from a vein in your arm.

4 Preparing for your Procedure

Required preparation for your blood urea nitrogen (BUN) test includes:

If your blood sample is being tested only for blood urea nitrogen, you can eat and drink a normally as you do.

If you blood sample will be used for additional testing, you may be required to fast for a certain amount of time before the test. You will be given specific instructions by your doctor.

5 What to Expect

Here’s what you can expect during and after your blood urea nitrogen (BUN) test.

During the blood urea nitrogen test, a member of your health care team will take a sample of your blood by inserting a needle into a vein located in your arm.

The blood sample is then sent to the lab for analysis. After the blood sample has been taken, you will be told to resume your daily routine activities.

6 Procedure Results

Results of the blood urea nitrogen test are measured in milligrams per deciliter (mg/dL) in the United States and millimoles per liter (mmol/L) internationally.

Generally, 7 to 20 mg/Dl (2.5 to 7.1 mmol/L) is considered to be normal. However, normal range may vary, depending on the reference range utilized by the lab and your age.

Ask your doctor to explain your results. The tendency of urea nitrogen levels to rise increases with age. Generally, a high blood urea nitrogen level means you kidneys are not functioning as well as they are supposed to.

But elevated urea nitrogen can also be due to the following:

If kidney damage is a concern, ask your doctor what factors may be adding to the damage and what steps you can take to try to control them.

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