What is BUN?

Blood Urea Nitrogen (BUN) is a test doctors use to check how well your kidneys are working and to get an idea of your overall health. It measures the amount of nitrogen, a waste product from breaking down proteins, in your blood. When your body processes protein, it creates urea, and your kidneys are responsible for removing this urea from your blood. If your kidneys aren't working properly, urea can build up in your blood, and the BUN test helps to detect this. However, BUN levels can also be affected by other things like dehydration or certain medications. Doctors usually look at BUN levels alongside other tests to understand how well your kidneys are doing their job and how healthy you are overall.

Why is BUN Important?

BUN is an essential marker for assessing kidney function. The kidneys play a crucial role in filtering waste products from the blood, including urea. Higher BUN levels can indicate potential issues with kidney function, while lower levels may suggest liver disease, malnutrition, or overhydration.

Monitoring BUN levels is vital for detecting and managing various health conditions, especially those affecting the kidneys. Elevated BUN levels may signify acute or chronic kidney disease, dehydration, congestive heart failure, urinary tract obstruction, gastrointestinal bleeding, tissue damage, Addison’s disease, or a high-protein diet. Conversely, low BUN levels can indicate liver damage, malnutrition, a low-protein diet, or overhydration.

Understanding Your BUN Test Results

BUN levels are typically reported in milligrams per deciliter (mg/dL) of blood. Normal BUN levels can vary depending on age, gender, and other factors, but generally fall between 7 to 20 mg/dL according to a few sources (CDC, American Kidney Fund, University of Rochester Medical Center).

Mayo Clinic Laboratories and Cleveland Clinic further broke the range down as follows:

  • 7-20 mg/dL for both males and females between 1-17 years old
  • Adult males: 8-24 mg/dL
  • Adult females: 6-21 mg/dL

Improving BUN and Kidney Function:

While specific interventions may vary depending on the underlying cause of abnormal BUN levels, general strategies for maintaining kidney health include:

  • Staying hydrated: Adequate fluid intake helps support kidney function and maintain BUN within a healthy range.
  • Following a balanced diet: Consuming a diet rich in fruits, vegetables, whole grains, and lean proteins can help promote kidney health and prevent complications.
  • Managing underlying health conditions: Effectively managing conditions such as diabetes, hypertension, and heart disease can help preserve kidney function and prevent complications.
  • Avoiding nephrotoxic substances: Limiting exposure to substances that can harm the kidneys, such as certain medications, toxins, and heavy metals, is essential for kidney health.
  • Regular monitoring: Regular check-ups with healthcare providers can help monitor kidney function and detect any abnormalities early on.

Where Can I Learn More?

American Kidney Fund - BUN Test for Kidney Disease

National Kidney Foundation - Understanding Your Lab Values


Scientific Literature:

Chen, Lan et al. “The association of blood urea nitrogen levels upon emergency admission with mortality in acute exacerbation of chronic obstructive pulmonary disease.” Chronic respiratory disease vol. 18 (2021): 14799731211060051. doi:10.1177/14799731211060051

Lan Q, Zheng L, Zhou X, Wu H, Buys N, Liu Z, Sun J and Fan H (2021) The Value of Blood Urea Nitrogen in the Prediction of Risks of Cardiovascular Disease in an Older Population. Front. Cardiovasc. Med. 8:614117. doi: 10.3389/fcvm.2021.614117