Blood Urea Nitrogen
Understanding Blood Urea Nitrogen
What is Blood Urea Nitrogen?
A Blood Urea Nitrogen test measures the level of urea nitrogen in the blood. This test is done to detect any kidney disease or damage, or if you are undergoing treatment for any known kidney disease. It is often done as part of routine health checkups to determine your kidney function.
Blood urea is the breakdown product of the amino acids which are present in proteins. When proteins break down, they produce nitrogen in the form of ammonia in the liver. The nitrogen combines with other chemicals in the liver to form the waste product called urea. This urea is released into the blood and carried to the kidneys where it is filtered out of the blood and flushed from the body through urine. Usually, healthy kidneys remove more than 90% of the urea the body produces, so determining blood urea levels can show how well your kidneys are working.
Your doctor may advise a Blood Urea Nitrogen test if you have risk factors like diabetes, high blood pressure, liver disease, etc. People with early-stage kidney disease may not show symptoms, but this test can help detect such kidney problems so that the treatment can be more effective. This test also helps determine the effectiveness of dialysis treatment in kidney disease patients. Usually, no special preparation is required for a BUN test. You may eat and drink as per your daily routine.
Test result ranges are approximate and may differ slightly between different labs depending on the methodology and laboratory guidelines. Talk to your doctor about your specific test results. Narrate your complete medical history to help the doctor correlate your clinical and laboratory findings. The results will help them determine your medical condition, make recommendations for lifestyle modifications such as diet and exercise, decide whether or not medication will be required to manage your kidney health, and formulate your overall treatment plan.
What is Blood Urea Nitrogen used for?
A Blood Urea Nitrogen test is done:
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As part of routine health checkups.
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In the case of signs and symptoms of kidney disease.
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To screen for kidney disease if you have risk factors like obesity, diabetes, high blood pressure, or a family history of kidney disease.
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To check for the effectiveness of ongoing treatment for kidney diseases.
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To help determine the effectiveness of dialysis treatment if someone is receiving hemodialysis or peritoneal dialysis.
What does Blood Urea Nitrogen measure?
A Blood Urea Nitrogen test measures the levels of urea nitrogen in the blood. Blood urea is a waste product that is formed in the liver when you eat food and the protein is metabolized into amino acids. This process leads to the production of ammonia that is further converted into urea. Both ammonia and urea are nitrogenous compounds. Your liver releases urea into the blood which is then carried out to the kidneys. In the kidneys, urea is filtered from the blood and flushed out of the body via urine. This is a continuous process, so a small amount of urea nitrogen always remains in the blood.
In the case of a kidney or liver disease, there is a change in the amount of urea present in the blood. If your liver produces urea in an increased amount or if there is any problem in kidney functioning, there might be difficulty in filtering out the waste products from the blood, which can result in increased urea levels in the blood.
Interpreting Blood Urea Nitrogen results
Interpretations
The reference range for BUN is as follows:
Age |
Reference range in mg/dL |
0 - 1 week |
3 - 25 |
1 week - 1 year |
4- 19 |
1 - 12 years |
5 - 18 |
12 - 60 years |
6 - 20 |
60 - 90 years |
8- 23 |
> 90 years |
10 - 31 |
Reference range may vary from lab to lab*