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Kidney Function

What is Blood Urea Nitrogen? Your Complete Guide

Urea is a waste product from protein breakdown, filtered out by your kidneys. When kidneys aren't working well, urea builds up in your blood.

💡Simply Explained

When your body breaks down protein (from food or muscles), it produces a waste called urea. Your kidneys are supposed to filter it out. If urea builds up, it means your kidneys might not be cleaning your blood well enough.

📏Normal Range

7 – 20mg/dL

Typical reference range. Your lab may use slightly different values.

LowNormalHigh
< 7 mg/dL7 – 20 mg/dL> 20 mg/dL

⬆️What High Blood Urea Nitrogen Means

Possible Causes

  • Dehydration (most common cause)
  • High-protein diet
  • Kidney disease
  • Heart failure
  • GI bleeding (blood proteins get digested into urea)
  • Urinary tract obstruction

Foods That Can Help

  • Drink plenty of water — dehydration is the #1 cause
  • Reduce high-protein meals temporarily
  • Watermelon and cucumber (natural diuretics)
  • Coconut water

⬇️What Low Blood Urea Nitrogen Means

Possible Causes

  • Low-protein diet
  • Severe liver disease
  • Overhydration
  • Malnutrition

Foods That Can Help

  • Increase protein intake: dals, paneer, eggs, nuts
  • Balanced meals with adequate calories

🏃Lifestyle Actions

If Your Blood Urea Nitrogen Is High

  • Hydrate well and retest — dehydration is the most common cause
  • If BUN stays high after hydration, get kidney function (creatinine, eGFR) checked
  • Check BUN/Creatinine ratio — helps distinguish kidney vs pre-kidney causes
  • Monitor blood pressure — hypertension damages kidneys

If Your Blood Urea Nitrogen Is Low

  • Increase dietary protein if diet-related
  • Get liver function tested if unexplained

🩺When to See a Doctor

High Blood Urea Nitrogen

Mildly elevated BUN after dehydration — rehydrate and retest. If high with high creatinine, see a doctor within a week for kidney evaluation.

Low Blood Urea Nitrogen

Low BUN is rarely urgent. Investigate if accompanied by other abnormalities.

🎯Did You Know?

Indian labs often report "Urea" in mg/dL (normal 15-40) while Western labs report "BUN" (normal 7-20). Same test, different units! BUN = Urea ÷ 2.14.

❓Frequently Asked Questions

What is Blood Urea Nitrogen?

When your body breaks down protein (from food or muscles), it produces a waste called urea. Your kidneys are supposed to filter it out. If urea builds up, it means your kidneys might not be cleaning your blood well enough.

What is the normal range for Blood Urea Nitrogen?

The typical normal range for Blood Urea Nitrogen is 7–20 mg/dL.

What causes high Blood Urea Nitrogen?

Dehydration (most common cause). High-protein diet. Kidney disease.

What causes low Blood Urea Nitrogen?

Low-protein diet. Severe liver disease. Overhydration.

How can I check my Blood Urea Nitrogen levels?

You can check your Blood Urea Nitrogen levels with a routine blood test. Upload your lab report to ScanHealth for an instant, plain-language explanation.

Check Your Blood Urea Nitrogen Results Instantly

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This guide is for informational purposes only and does not constitute medical advice. Reference ranges may vary by lab. Always consult a qualified healthcare provider for diagnosis and treatment.