BUN · high result
What does a high BUN mean?
Short answer
BUN (blood urea nitrogen) rises with dehydration, a high-protein diet, gastrointestinal bleeding, heart failure, steroids and reduced kidney function. It's read with creatinine: a BUN-to-creatinine ratio above about 20 suggests dehydration or bleeding rather than kidney disease, while both rising together points to the kidneys.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
What is the normal range for BUN?
- age 18+: 7.00 – 20.0 mg/dL
Often reflects dehydration, high-protein diets, or reduced kidney function.
Full reference table, citations and testing options: BUN biomarker page.
What are the common causes of high BUN?
- Dehydration
- High-protein diet or protein supplements
- Reduced kidney function
- Gastrointestinal bleeding, heart failure, shock
- Glucocorticoids, tetracyclines, catabolic states
What symptoms go with high BUN?
- Usually none
- Thirst, dark urine if dehydrated
What do clinicians usually check next?
- Interpret with creatinine and eGFR
- Repeat hydrated
- Stool blood test if bleeding is possible
How do you recheck BUN?
Prices are cash-pay; every order adds one $6 lab processing fee. Physician authorization is included; no insurance or referral needed.
| Test or panel | Type | Price | Fasting | Results |
|---|---|---|---|---|
| Basic Metabolic Panel | Test · 8 biomarkers | $20.99 | Yes | 1–3 business days |
Common questions
Is high BUN a kidney problem?
Only when creatinine and eGFR agree. On its own, high BUN is more often dehydration or diet.
Sources
Educational content, not a diagnosis. Lab results are one input; a clinician interprets them with your history and exam.