🫘 Kidney Function

BUN: What It Means for Your Health

Blood Urea Nitrogen measures the amount of urea nitrogen in your blood. Urea is produced in the liver when proteins are broken down and is filtered out by the kidneys. BUN reflects both kidney function and protein intake. Unlike creatinine, BUN is affected by diet, hydration, and liver function, making it a less specific kidney marker. The BUN/creatinine ratio helps distinguish between different causes of kidney dysfunction.

Full Name
Blood Urea Nitrogen (BUN)
Normal Range
7–20 mg/dL
Also Known As
Blood Urea Nitrogen, Urea

Reference Range

LowNormal: 7–20 mg/dLHigh

Reference ranges may vary between laboratories, age groups, and sexes. The values shown are general adult reference ranges. Always compare your results to the specific range provided by your testing laboratory.

What Is BUN?

Blood Urea Nitrogen measures the amount of urea nitrogen in your blood. Urea is produced in the liver when proteins are broken down and is filtered out by the kidneys. BUN reflects both kidney function and protein intake. Unlike creatinine, BUN is affected by diet, hydration, and liver function, making it a less specific kidney marker. The BUN/creatinine ratio helps distinguish between different causes of kidney dysfunction.

Commonly included in:

Basic Metabolic Panel (BMP)Kidney Function PanelComprehensive Metabolic Panel

What Does High BUN Mean?

Above 20 mg/dL

Elevated BUN can indicate kidney disease, dehydration, high-protein diet, gastrointestinal bleeding (blood proteins are digested and raise BUN), heart failure, burns, or medications that affect kidney blood flow. A high BUN/creatinine ratio (above 20:1) suggests dehydration or pre-renal causes rather than intrinsic kidney disease.

What Does Low BUN Mean?

Below 7 mg/dL

Low BUN may indicate liver disease (reduced urea production), malnutrition, overhydration, pregnancy, or a very low-protein diet. It is usually not concerning on its own.

Related Biomarkers in Kidney Function

Creatinine
Waste product from muscle metabolism filtered by the kidneys.
Range: 0.6–1.2 mg/dL
eGFR
Estimate of how well your kidneys filter waste from your blood.
Range: 90–120 mL/min/1.73m2

Track Your BUN Over Time

Upload your blood test results to Hemoly and see how your BUN levels change over time. Get trend analysis, educational insights, and a personal health timeline.

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Medical Disclaimer

This information is for educational purposes only and is not intended as medical advice, diagnosis, or treatment. Reference ranges may vary between laboratories. Always consult a qualified healthcare professional for interpretation of your blood test results and before making any health decisions.