What It Measures
BUN measures the amount of urea nitrogen in your blood. Urea is produced when the liver breaks down dietary and cellular proteins, and healthy kidneys filter it out into urine. The test reflects how well your kidneys are clearing waste and can also indicate protein intake levels and hydration status.
Blood Urea Nitrogen (BUN) is a waste product formed in the liver when protein is metabolized and filtered out by the kidneys. It is a key marker of kidney function and protein metabolism, making it essential for assessing renal health and hydration status. Elevated or low BUN levels can signal a range of conditions from kidney disease to liver dysfunction.
Current Value
What High Means
Elevated BUN may indicate impaired kidney function (acute or chronic kidney disease), dehydration, high-protein diet, gastrointestinal bleeding (digested blood acts as a protein source), congestive heart failure (reduced blood flow to kidneys), urinary tract obstruction, shock, burns, or use of certain medications (e.g., corticosteroids, tetracyclines). It can also rise with catabolic states such as fever, infection, or severe stress.
Possible Symptoms
Fatigue, nausea, vomiting, loss of appetite, confusion or difficulty concentrating, swelling in legs or feet (edema), decreased urine output, dark-colored urine, muscle cramps, itchy skin, and in severe cases uremic symptoms including metallic taste and shortness of breath.
What Low Means
Low BUN may indicate liver disease or liver failure (reduced urea production), malnutrition or low protein intake, overhydration (dilution effect), celiac disease or malabsorption syndromes, or late-stage pregnancy (due to increased blood volume and GFR). It is less commonly clinically significant than elevated BUN but warrants evaluation when persistently low.
Possible Symptoms
Often asymptomatic. When caused by underlying conditions: fatigue, weakness, muscle wasting, poor wound healing, edema (from low protein/albumin), abdominal swelling (if liver-related), and general malaise.
Risk Factors
Chronic kidney disease, acute kidney injury, congestive heart failure, dehydration, gastrointestinal bleeding, urinary tract obstruction, diabetes, hypertension, high-protein diets, liver disease, malnutrition, sepsis, and use of nephrotoxic medications.
Actionable Advice
Supplements
- •NAC (N-Acetyl Cysteine)
- •Omega-3 fatty acids
- •Alpha-lipoic acid
- •Astragalus
- •Probiotics
- •Vitamin D
- •CoQ10
- •B vitamins
Diet & Lifestyle
- •Stay well-hydrated — drink adequate water throughout the day
- •Moderate protein intake based on your activity level and kidney health
- •Manage blood pressure and blood sugar to protect kidney function
- •Reduce NSAID and nephrotoxic medication use when possible
- •Exercise regularly but avoid excessive protein supplementation
- •Limit processed foods high in sodium which stress the kidneys
- •Monitor kidney function regularly if you have diabetes or hypertension
- •Avoid chronic dehydration from excessive caffeine or alcohol
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Historical Trend
Resources & Studies
All Readings
| Date | Value | Change |
|---|---|---|
| 2026-01-28 | 18 mg/dL | -1.0 |
| 2025-08-25 | 19 mg/dL | +4.0 |
| 2025-06-27 | 15 mg/dL | — |