Blood Urea Nitrogen (BUN): Normal Vs. High/Low

By Jordan Stachel, MS, RDN, CPT

Sometimes going for bloodwork can feel overwhelming, especially when you are trying to interpret the results. Blood urea nitrogen (BUN) is one test that is commonly taken to assess kidney function. Read this article for everything you need to know.

What Is BUN?

BUN measures the amount of urea nitrogen in the blood. Healthy kidneys filter urea nitrogen and remove other waste products from your blood. The filtered waste products leave your body through urine. If there is kidney damage, the kidneys may have a harder time getting rid of urea nitrogen. If this is the case, a BUN test may yield a higher result than normal.

BUN levels are run fairly routinely and will definitely be run if your healthcare provider suspects that you may have issues with renal function. There will likely be other blood markers also tested in order to get to the root cause of the issue. A provider may run other levels, such as creatinine or the glomerular filtration rate (GFR). Both of these markers also measure general kidney function.

Urea nitrogen is also a normal waste product that the body makes when you eat protein. Normally, the urea nitrogen will leave the body when you urine.

Who Should Get BUN Tested?

There may be several reasons that a healthcare provider may want to run BUN levels. Some of these include:

• If kidney damage is suspected
• If you have a family history of kidney disease
• If you have other health conditions that increase your risk for kidney disease, such as diabetes or heart disease
• If you are experiencing certain symptoms like more frequent urination, differences in urination, loss of appetite, and swelling of the hands, feet, or ankles

What Are Normal BUN Levels?

BUN levels vary based on age and gender. Levels that are considered normal are:

• Children 1-17 y/o: Between 7 and 20 mg/dL
• Adult Females: Between 6 and 21 mg/dL
• Adult Males: Between 8 and 24 mg/dL

If your levels are too high, there could be several causes. Some of these include:

• Kidney damage
• Eating too much protein
• Being dehydrated
• Being on certain medications
• Stress
• Bleeding

Low levels can be due to:

• Not eating enough protein in the diet
• A general state of malnutrition
• Certain diseases, such as liver disease
• Being pregnant

How to Improve BUN Levels

If you get your BUN levels tested and they come back abnormal, it is important to work with a qualified healthcare provider to optimize levels. This involves getting to the root cause of why the levels are abnormal and fixing the source of the issue.

In general, if your BUN levels are too high, there may be some steps to take to bring your levels back down to the normal range. Some of these things include:

• Eat fewer protein-based foods. Protein comes from various food sources. Some high-protein foods include meat, fish, soy, dairy, and certain protein supplements.
• Make sure you are well hydrated. Being dehydrated can be a cause of high BUN levels, so drinking enough water is important.

In general, if your BUN levels are too low, there are some dietary elements to think about to help raise your levels back to normal. Mainly, you can work with a healthcare provider to help add more protein to your diet. Focus on some protein-based foods using these meal and snack ideas:

• Breakfast: Greek yogurt (protein) with peanut butter, berries, and granola
• Snack: hard-boiled eggs (protein) with sliced veggies and hummus
• Lunch: salmon (protein) salad with quinoa, cooked veggies, cheese, and dressing of choice
• Snack: turkey (protein) roll-ups with sliced cheese, mustard, sliced veggies (cucumber, carrot)
• Dinner: burger bowl with lean ground beef (protein), wild rice, broccolini, and sauce of choice

What to Expect When Getting a BUN Blood Test

If you are going to get your blood tested to see where your BUN levels are, it is a fairly straightforward blood test. There is nothing needed to be done to prep for the test. During the test, a healthcare provider will collect a sample of blood. Results are typically ready quickly, and there is no downtime.

If you are having other biomarkers collected during this time, you may need to fast, so it is always a good idea to check with your provider before going for the test.

Take Control of Your Health With Everlywell

Everlywell offers testing from the comfort of your own home. With fast and easy telehealth visits, you can take the first steps towards figuring out if you need to have your BUN levels drawn. Everlywell 360 is another option that also looks at over 83 biomarkers to provide you with a more complete view of your health.

Whether you are experiencing certain symptoms or simply want to take a proactive approach towards your health and wellbeing, Everlywell can be your partner on your wellness journey.

References

1. Blood urea nitrogen (BUN) test - Mayo Clinic. Last reviewed August 5, 2023. Accessed September 7, 2025. https://www.mayoclinic.org/tests-procedures/blood-urea-nitrogen/about/pac-20384821
2. Professional CCM. Blood urea nitrogen (BUN) test. Cleveland Clinic. Published September 5, 2025. Accessed September 7, 2025. https://my.clevelandclinic.org/health/diagnostics/17684-blood-urea-nitrogen-bun-test
3. BUN (Blood urea nitrogen). Last reviewed October 27, 2024. Accessed September 7, 2025. https://medlineplus.gov/lab-tests/bun-blood-urea-nitrogen/
4. Hosten AO. BUN and Creatinine. Clinical Methods - NCBI Bookshelf. Published 1990. Accessed September 7, 2025. https://www.ncbi.nlm.nih.gov/books/NBK305/