Understand your Blood Urea Nitrogen (BUN) Blood Test Results…

This page helps you to understand blood test results for BUN and gives you the reference range to determine if your lab test results mean that you have high cholesterol, low cholesterol or normal cholesterol levels. 

We outline the risk factors associated with raised BUN levels.

Reference Ranges for BUN:

Measurement unit Metric Optimal Risk
US Conventional Units mg/dl 7-22 <7 or >22
Standard International Units mmol/L 2.5-7.9 <2.5 or >7.9
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What is BUN

A Blood urea nitrogen (BUN) test reveals important information about how well your kidneys and liver are working. A BUN test measures the amount of urea nitrogen that’s in your blood.

Your body typically forms and gets rid of urea nitrogen as follows:

  • Your liver produces ammonia — which contains nitrogen — after it breaks down proteins used by your body’s cells.
  • The nitrogen combines with other elements, such as carbon, hydrogen and oxygen, to form urea, which is a chemical waste product.
  • The urea travels from your liver to your kidneys through your bloodstream.
  • Healthy kidneys filter urea and remove other waste products from your blood.
  • The filtered waste products leave your body through urine.

A BUN test can reveal whether your urea nitrogen levels are higher than normal, suggesting that your kidneys or liver may not be working properly [57].

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Function of BUN

Urea is a waste product formed in the liver when protein is metabolized into its component parts (amino acids).

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Risk factors associated with BUN

BUN concentrations may be elevated when there is excessive protein breakdown (catabolism), significantly increased protein in the diet, or gastrointestinal bleeding (because of the proteins present in the blood).

Increased BUN levels may suggest impaired kidney function. This may be due to acute or chronic kidney disease, damage, or failure. It may also be due to a condition that results in decreased blood flow to the kidneys, such as congestive heart disease, shock, stress, or severe burns, to conditions that cause obstruction of urine flow, or to dehydration.

Low BUN levels are not common and are not usually a cause for concern. They may be seen in severe liver disease, malnutrition, and sometimes when a person is overhydrated (too much fluid volume), but the BUN test is not usually used to diagnose or monitor these conditions.

If one kidney is fully functional, BUN concentrations may be normal even when significant dysfunction is present in the other kidney [58].

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Notable variations by Demographic Group

BUN levels tend to increase with age.  BUN levels in very young babies are about 2/3 of the levels found in healthy young adults, while levels in adults over 60 years of age are slightly higher than younger adults.

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Diet to improve BUN

Phosphorus is a mineral found in almost all foods. It works with calcium and vitamin D to keep your bones healthy. Healthy kidneys keep the right amount of phosphorus in your body. When your kidneys are not working well, phosphorus can build up in your blood. Too much phosphorus in your blood can lead to weak bones that break easily [61].

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Supplements for BUN

Vitamin D and B9 (methylfolate) supplements have been shown to help prevent some common side effects of kidney disease, such as bone disease and anemia. Regular multi-vitamins may not be right for you at present if you have kidney problems. They may have too much of some vitamins and not enough of others. There are supplements formulated for people with impaired kidney function.

People who have been diagnosed with kidney disease should avoid herbal supplements unless prescribed by their doctor as some herbal products can cause harm to your kidneys [63].

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Exercise to improve BUN

Exercise is a great way to improve your kidney health as it helps to remove toxins from the body and also helps to control blood pressure….two of the leading causes of kidney disease. It is advisable to build up slowly when beginning a new exercise regime.  Overexerting yourself when you’re not fit can put a strain on your kidneys, especially if you exercise so much that you cause excessive breakdown of muscle tissue.

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Sleep for BUN

Researchers from Boston’s Brigham and Women’s Hospital evaluated the sleep habits of thousands of women and found too little sleep was related to a more rapid decline in kidney function. Women who slept five hours or less a night had a 65 percent greater risk of rapid decline in kidney function, compared with women sleeping seven to eight hours a night, the investigators discovered.

The same study suggests that disturbance in the body’s natural circadian might also play a role in reduced kidney function. The kidney is timed to work differently during the night than during the day because the demands on the body are different [64].