BUN (Blood Urea Nitrogen)
BUN measures nitrogen waste from protein breakdown. Elevated BUN can indicate dehydration, high protein intake, or kidney issues — best interpreted alongside creatinine.
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What BUN (Blood Urea Nitrogen) measures
When you digest protein, your liver produces urea as a waste product, and your kidneys filter it out. BUN measures the nitrogen portion of that urea in blood. The BUN/creatinine ratio helps doctors distinguish dehydration (high ratio) from true kidney problems (proportional rises).
Normal ranges
Reference ranges may vary slightly by lab. Always use the range provided on your specific test report.
What affects your bun (blood urea nitrogen) level
- Dehydration (most common cause of mild elevation)
- High-protein diet or protein supplements
- GI bleeding (digested blood acts like a high-protein load)
- Kidney impairment
- Heart failure (reduced kidney perfusion)
- Medications: steroids, tetracyclines
- Aging (gradual rise is normal)
Foods that may help
Water — consistent intake
Hydration is the single biggest lever for BUN
Cucumber, watermelon, leafy greens
High water content helps hydration status
Moderate (not low) protein
Don't overcorrect — adequate protein is still important
Olive oil and fatty fish
Anti-inflammatory fats support kidney health
Fewer processed and high-sodium foods
Reduces kidney workload
When to see your doctor
Persistent BUN above 30, or a BUN/creatinine ratio above 20:1, warrants evaluation. Always interpret BUN alongside creatinine and eGFR — BUN alone can mislead.
Related biomarkers
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Educational content only · Not medical advice