Lab marker · High

High Blood Urea Nitrogen (BUN): what it means

A Blood Urea Nitrogen (BUN) result above the normal range is considered high. Here is what a raised Blood Urea Nitrogen (BUN) can point to, and when it is worth discussing with a doctor.

Reference range: 7–20 mg/dL; BUN/creatinine ratio >20 suggests dehydration or GI bleed

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What a high Blood Urea Nitrogen (BUN) can mean

  • Dehydration — most common cause; ratio with creatinine is high.
  • Chronic kidney disease — usually with elevated creatinine and reduced eGFR.
  • Acute kidney injury — rapid rise of both BUN and creatinine.
  • Upper gastrointestinal bleed — blood acts as a protein meal, raising BUN.
  • High protein intake, corticosteroids — modest rises.
  • Congestive heart failure — reduced renal perfusion.

When to discuss with a doctor

BUN elevation should always be interpreted with creatinine and eGFR. Mediora.AI computes the BUN/creatinine ratio when both values are present and uses it to flag the dehydration-vs-kidney-disease pattern.

Conditions this can relate to

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Mediora.AI is informational - interpretation, not a diagnosis. A single out-of-range value is common and often benign; always discuss decisions with your doctor.