bun (blood urea nitrogen)
Kidney FunctionBlood sampleResults 24 hrsNo fasting
BUN (Blood Urea Nitrogen)
Blood Urea Nitrogen (BUN) measures the amount of urea, a waste product, in your blood. It's a common test for kidney function and hydration status.
Sample
Blood
Results
24 hrs
Fasting
Not required
Follow-up
Optional add-on
What this test detects
Urea nitrogen
Enzymatic kinetic · serum
Quantitative · mg/dL
When to get this test
Kidney function
Helps assess how well your kidneys are removing waste from the blood.
Hydration status
BUN can rise with dehydration, providing clues about fluid balance.
Monitoring kidney conditions
Used to track kidney health over time, often with creatinine.
How to prepare
01
No special preparation needed.
Common questions
What is BUN used for?
BUN reflects a waste product that the kidneys normally remove. High levels can suggest reduced kidney function or dehydration, while low levels are less common.
Why is BUN paired with creatinine?
Together, BUN and creatinine give a fuller picture of kidney function. Their ratio can help distinguish between different causes of changes in kidney markers.