BUN - blood test

BUN - Blood Test

A BUN test, also known as a Blood Urea Nitrogen test, is a test of one’s kidney function. It evaluates how well the kidneys are filtering the urea, nitrogen-containing waste, out of the bloodstream. The BUN test is often performed alongside a creatinine test, which is another marker of kidney health.


It is not necessary to fast or make changes in your diet before the BUN test. The same applies for medication. It is important to tell your doctor about what and when you last ate as well as all medications you have been taking.


The procedure for a BUN test is simple. An individual will usually be asked to sit or lay down on a bed. A technician or nurse will then take a sample of the individual’s blood out of their arm. They will clean the area, place a needle in the vein and draw the blood sample out. The sample is then sent off to a laboratory for testing and analysis.


There are two main types of BUN tests: a serum BUN and a urine BUN. A serum BUN is done using a blood sample obtained through a venipuncture (blood drawn from the vein). A urine BUN is done using a sample of urine.


The risks involved with a BUN test are minimal. The only risk associated with this procedure is the risk involved with any other blood or urine test. This includes any risk of infection from the needle, as well any adverse effects associated with taking a blood or urine sample.

Why is a BUN Test Done?

A BUN test is usually done in order to assess a person’s kidney function. The BUN test helps to evaluate how well the kidneys are filtering out urea, a nitrogen-containing waste product, out of the blood. It is often done alongside a creatinine test, another marker of kidney health, in order to get a better picture of how the kidneys are functioning.

When is a BUN Test Done?

A BUN test is usually done if a doctor suspects that a person is experiencing some sort of kidney issue or disease. It may also be done if a person is taking medications known to affect kidney function or is experiencing symptoms such as excessive thirst, fatigue, and/or weight loss. It may also be done as part of a routine blood panel.

Normal Range of BUN Levels

The normal range of BUN levels in the blood is between 6 and 22 milligrams/deciliter (mg/dl). A person’s BUN level may increase if they are dehydrated or if they have certain medical conditions, such as kidney disease, uncontrolled diabetes, and high blood pressure.