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Blood Urea Nitrogen - BUN

What does the Blood Urea Nitrogen - BUN blood test mean? Get a free analysis of your blood test now. Here's what you get with our free analysis:

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The Blood Urea Nitrogen (BUN) test measures the amount of urea nitrogen in the blood. Urea is a waste product formed when protein is broken down in the liver. It's then filtered out by the kidneys and excreted in urine. This test is primarily used to evaluate kidney function and can also provide information about overall health. Elevated BUN levels may indicate kidney dysfunction, dehydration, or certain medical conditions affecting protein metabolism. Conversely, low BUN levels might suggest liver problems or malnutrition. The BUN test is often interpreted alongside other tests, such as creatinine, to provide a more comprehensive assessment of kidney function and overall health status.

Acceptable Range:   7 to 20
Ideal for Women:   6-20
Ideal for Men:   8-20
Ideal for Girls:   5-18
Ideal for Boys:   7-20
Test Method: blood

What do readings below 7 mg/dL for Blood Urea Nitrogen - BUN mean?

A low BUN reading (below 7 mg/dL) may indicate:

  1. Liver disease: The liver may not be producing enough urea.
  2. Malnutrition or a low-protein diet: Not enough protein is being metabolized to produce urea.
  3. Overhydration: Excess fluid in the body can dilute BUN concentration.
  4. Pregnancy: BUN levels naturally decrease during pregnancy.
  5. Severe muscle wasting (atrophy): Less creatinine is produced, affecting the BUN/creatinine ratio.

Low BUN alone isn’t usually cause for concern but may warrant further investigation if persistent or accompanied by other symptoms.

What do readings above 20 mg/dL for Blood Urea Nitrogen - BUN mean?

A high BUN reading (above 20 mg/dL) may indicate:

  1. Kidney dysfunction: The kidneys aren’t effectively filtering urea from the blood.
  2. Dehydration: Concentrated blood leads to higher BUN levels.
  3. Heart failure: Reduced blood flow to kidneys can elevate BUN.
  4. Gastrointestinal bleeding: Blood in the digestive tract can increase protein breakdown.
  5. Certain medications: Some drugs can affect BUN levels.
  6. High-protein diet: Excessive protein intake can temporarily raise BUN.
  7. Severe burns or infections: These conditions can increase protein catabolism.

High BUN often requires further investigation to determine the underlying cause and appropriate treatment.

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