To convert blood urea nitrogen (BUN) from mg/dL to mmol/L, divide the value by 2.8. For example, 28 mg/dL equals 10 mmol/L.
Urea (BUN-based) Calculator
Conversion settings
Understanding Urea vs BUN
In many laboratory reports, urea is measured as Blood Urea Nitrogen (BUN). While the terms are related, they are not identical. BUN measures only the nitrogen portion of urea.
Because of this, the conversion factor for BUN differs from creatinine, glucose, or cholesterol.
Correct unit conversion is essential when comparing international kidney function results.
The Correct Conversion Formula
Formula
mmol/L = mg/dL ÷ 2.8
You may also see the alternative expression:
mmol/L = mg/dL × 0.357
Both produce the same result.
Example Calculations
14 mg/dL ÷ 2.8 = 5 mmol/L
28 mg/dL ÷ 2.8 = 10 mmol/L
42 mg/dL ÷ 2.8 = 15 mmol/L
Always use 2.8 as the divisor when converting BUN from mg/dL to mmol/L.
What Urea (BUN) Indicates
Urea is a waste product formed in the liver after protein metabolism. The kidneys filter urea from the blood and excrete it in urine.
Elevated BUN levels may be associated with:
- Dehydration
- Reduced kidney function
- High protein intake
- Gastrointestinal bleeding
- Certain medications
Low levels may be seen in liver disease or severe malnutrition.
Interpreting Urea in mmol/L
Typical reference ranges (may vary by lab):
Approximately 2.5–7.8 mmol/L
Values above this range may indicate impaired kidney filtration or dehydration. However, interpretation must consider creatinine levels and overall clinical context.
Why Accurate Conversion Matters
Kidney function assessment often relies on multiple parameters, including:
- Serum creatinine
- Estimated GFR (eGFR)
- BUN/Creatinine ratio
- Urinalysis findings
Incorrect conversion can lead to misunderstanding of kidney status, especially when reviewing international guidelines or research data.
Situations Where Conversion Is Needed
You may need to convert BUN units when:
- Comparing lab reports from different countries
- Reviewing international clinical guidelines
- Using kidney disease staging tools
- Tracking long-term results across healthcare systems
Using an automated calculator ensures precise and consistent results.
Frequently Asked Questions
How do I convert BUN from mg/dL to mmol/L?
Divide the mg/dL value by 2.8.
Is this the same as creatinine conversion?
No. Creatinine uses a different factor (× 0.0884). BUN uses ÷ 2.8.
Why is the conversion factor 2.8?
The factor reflects the molecular relationship between nitrogen content and total urea concentration.
Can high BUN alone diagnose kidney disease?
No. BUN must be interpreted alongside creatinine, eGFR, hydration status, and clinical findings.
Final Words
Urea (BUN) is an important marker of kidney function and hydration status. Converting values accurately from mg/dL to mmol/L ensures clarity when reviewing international laboratory reports or medical guidelines.
Always discuss abnormal results with a qualified healthcare professional.