Biomarker education

BUN: What It Measures & Why People Track It

Also called: Blood urea nitrogen, Urea nitrogen

BUN measures a waste product from protein breakdown, often reported with creatinine.

General biomarker education — not personalized medical advice. Learn more

Result on your report

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BUN

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Range: Low – High

LowReference intervalHigh

What it generally measures

The liver produces urea as protein is broken down; the kidneys clear it into urine. Labs report the nitrogen portion of urea circulating in blood.

Common units on reports: mg/dL

Why people track it over time

BUN is frequently reviewed together with creatinine as part of kidney-related lab context. Diet, hydration, and other factors can move it independent of kidney function.

Changes over time do not by themselves establish a diagnosis. Learn more

Questions you might ask a healthcare professional

Questions to bring

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Ask how BUN and creatinine compare on this report.

Mention hydration, recent diet, or medications your clinician has said may matter.

Ask what the BUN-to-creatinine ratio, if calculated, is used for in your case.

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Reference range

BUN reference range

What the range on your report means for this marker.

Panel guide

Related panel guide

Understand the broader panel this marker appears on.

Related biomarker

Creatinine

Creatinine is a waste product measured in blood and often used when assessing kidney-related lab context.

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