Can this result diagnose a condition on its own?

No. Laboratory results are interpreted with symptoms, medical history, specimen conditions and related tests.

Which reference range should I use?

Start with the performing laboratory's own reference interval; clinical cutoffs, when relevant, are separate sourced thresholds used for a specific purpose.

When should I discuss the result with a healthcare professional?

Results that are clearly outside range, persistent, symptomatic or unexpected should be reviewed by a healthcare professional.

Information about a laboratory test

Low BUN: What Does It Mean?

Low BUN can occur with low protein intake, excess body water or severe impairment of liver urea production, among other causes.

Test summary

Test name: BUN
Abbreviations: BUN
Category: Nephrology / Nitrogen Waste
Panel: Renal Function / Basic Metabolic Panel
Specimen: Serum / plasma
Common units: mg/dL, mmol/L

What does the test measure?

Measures the amount of nitrogen in blood that comes from urea, a waste product of protein metabolism.

Why is the test ordered?

Commonly interpreted with creatinine to help assess kidney function, hydration and selected metabolic contexts.

Information about a low result

Low BUN can occur with low protein intake, excess body water or severe impairment of liver urea production, among other causes.

Information about a high result

High BUN can occur with reduced kidney function, dehydration, increased protein breakdown or gastrointestinal bleeding.

Reference and clinical context

Start with the performing laboratory's reference interval, unit and specimen conditions. Numeric information on this page is stored as sourced example intervals or clinical thresholds.

Reference range 1

>= 6 – <= 20 mg/dL

Population: Adults
Age range: 18
Specimen: Serum / plasma

Example adult BUN reference interval

The source presents these values as a common example reference interval. Laboratory method, age and clinical context can change the range; the user's own report takes priority.

Reference ranges may vary by laboratory, method used, age, sex, pregnancy status, and clinical context. The reference range on your own laboratory report takes precedence.

Interpretation notes

BUN is not kidney-specific. Creatinine, eGFR, hydration and the clinical context should be considered together.

Related specialties

Nephrology
Internal Medicine
Family Medicine

Frequently asked questions

Sources

Comprehensive Metabolic Panel — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2026 · Example adult intervals for ALT, AST, ALP, albumin, bilirubin, total protein, BUN, creatinine and electrolytes · Verified: Aug 12, 2026
Creatinine Test — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2026 · Creatinine limitations and use with eGFR, BUN and urine testing · Verified: Aug 12, 2026
BUN - Blood Test — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2026 · BUN meaning, kidney/liver/hydration context and example interval · Verified: Aug 12, 2026