For patients that will hear a doctor order a BUN (blood urea nitrogen) test, they may wonder precisely what that is, how it is done, and what it measures. The BUN test will take a sample of blood and measure the amount of nitrogen in it. Nitrogen in the blood comes from urea, a waste product that is made from proteins breaking down in the body. While urea is in the liver and flushed through the urine, when it makes its way to the blood vessels there is something wrong.
BUN Blood Test
Measuring the nitrogen from urea in the blood can tell the doctor how the kidneys are working in the body. It can show rising levels of nitrogen that will symbolize dehydration, high protein diets, heart failure, or a lessening in the working of the kidneys. It can also show lowering in the levels of nitrogen in the blood. This will show liver disease or a possible late stage pregnancy. Nitrogen in the blood found by BUN blood tests can help the diagnosis of many things, and it can track the success or failure of some kidney function treatments.
BUN Lab Test Ordering
Doctors order a BUN lab test to check for many things:
- Dehydration – which shows with a high BUN test result.
- Working kidneys – which shows with a normal BUN test result.
- Kidney disease or disorder – which shows with a high BUN test.
- Check kidney disease treatment – shows in the changes of subsequent BUN test.
Any of these can tell the doctor much about the waste removal process in the body.
How to Do a BUN Test
Do not eat meat or other protein laden items in the day before a BUN test; this is for the full 24 hours prior to the blood test. Blood will be drawn after cleaning the area with an alcohol swab. Blood will be drawn by syringe or vacuum collection, and then that blood will be sent to the lab for testing. There will be a cotton ball or gauze on the site of the blood draw and bandage. While there may be bruising and slight soreness from the procedure, there should be few other side effects from it. Results will come straight from the lab, and their rates for normal values will depend on the facility doing the testing.
Normal BUN Tests
The normal test results have a slight variation, check with the lab to determine their value for normal for best results.
- BUN test ranges – 10mg/dl – 20 mg/dl
- BUN to creatinine ranges (over 12 months age) 10:1 to 20:1
- BUN to creatinine ranges (under 12 months age) up to 30:1
Many things like conditions in the individual, age of the tester, and the medications that one is on can hinder results of the test. Be sure that your testing agency lab knows precisely all the conditions and the medications on before blood is drawn for the test.
BUN testing is a helpful test that a doctor may order to check for any kidney function abnormality. This test can be a great long term chart to plot out rising or falling numbers.
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