Blood Urea Nitrogen (BUN), Pre-Contrast, Serum/Plasma — Mass Concentration
Measures urea nitrogen in blood before an imaging contrast procedure to help assess kidney function and identify possible contrast-related risks.
["This blood test checks kidney function before contrast is given and may be repeated afterward if directed."]
Key facts at a glance
- LOINC
- 72270-2
- Short code
- BUN pre contrast SerPl-mCnc
- Synonyms
- BUN pre contrast SerPl-mCnc
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Critical range
- — – 100 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84484
- SNOMED
- 302774002
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What is this test?
The blood urea nitrogen (BUN) test measures a waste product called urea in your blood. Urea forms when your body breaks down protein, and it is removed through the kidneys. This version is collected before contrast material is given for an imaging procedure.
Why might I need this test?
A pre-contrast BUN test helps clinicians understand how well your kidneys are filtering waste before an imaging study. Along with other information, the result may be used to assess kidney function, guide hydration, and determine how your procedure should be planned.
How is the test performed?
A small sample of blood is drawn from a vein and sent to a laboratory for analysis. The sample is usually collected before you receive iodinated contrast material, and your care team may also request a follow-up test afterward.
How do I prepare for the test?
BUN testing usually does not require fasting. Follow any instructions provided for your imaging procedure, and tell your care team about kidney disease, dehydration, pregnancy, or allergies to contrast. If you have been told to limit fluids for a medical reason, do not increase your fluid intake without guidance.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A higher BUN level may occur with reduced kidney filtration, dehydration, or increased protein breakdown. A lower level can occur in some liver conditions or with excessive fluid dilution. The result is interpreted with other kidney and clinical measurements, so an isolated abnormal value does not by itself establish a diagnosis.
Short name
Pre-contrast BUN test
Frequently asked questions
Does this test use the same blood sample as other pre-procedure tests?
Is the pre-contrast BUN different from a routine BUN test?
Will I need another BUN test after the procedure?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy