Interpret Your Blood Urea Nitrogen Results
Enter your BUN value below and get an instant, free AI interpretation — a plain-English explanation checked against WHO/IFCC reference ranges.
Medical Disclaimer
This AI-generated interpretation is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Results may vary based on individual health factors not captured here.
Always consult a qualified healthcare professional before making any health decisions. Read full disclaimer →
Blood Urea Nitrogen Normal Ranges
BUN measures the amount of nitrogen in urea, a waste product formed in the liver from protein metabolism.
| Age Group | Reference Range | Unit | Notes |
|---|---|---|---|
| Adults (18–64) | 7 – 20 | mg/dL | — |
Also reported in: mmol/L.
Why Doctors Order the Blood Urea Nitrogen Test
The BUN:creatinine ratio is a key diagnostic tool. A ratio >20:1 suggests pre-renal causes (dehydration, heart failure, GI bleeding) where urea is elevated disproportionately to creatinine.
How to Enter Your BUN Result
Blood Urea Nitrogen can be reported in mg/dL or mmol/L. Choose the unit printed next to your result on the lab report so it is compared with the matching reference range.
What a Low or High BUN Can Be Associated With
Below the reference range
- Liver failure (urea synthesis reduced)
- Malnutrition or very low protein diet
- Overhydration
- SIADH (dilutional)
Above the reference range
- Dehydration and pre-renal azotemia (disproportionate BUN rise)
- Kidney disease (elevated BUN + creatinine)
- High protein diet
- GI bleeding (blood is digested and absorbed as protein, raising BUN)
- Catabolic states (sepsis, corticosteroids, burns)
These are common associations, not a diagnosis. A single result is read alongside your symptoms, history and other tests — discuss it with your doctor.
What Can Change Your BUN Result
Before you read too much into a result, consider whether any of these applied:
- High protein diet (raises BUN)
- GI bleeding (digested blood raises BUN)
- Corticosteroids (increase protein catabolism, raising BUN)
- Liver disease (reduces urea synthesis, lowering BUN)
Preparing for the test: No special preparation required. Inform your doctor of your dietary protein intake and any GI bleeding symptoms.
Symptoms That Often Prompt BUN Testing
- Fatigue
- Nausea
- Confusion or altered consciousness (uremia)
- Reduced urine output
- Edema
Want the full clinical guide to Blood Urea Nitrogen?
Reference ranges, causes, symptoms, preparation, and FAQs.