What it is: A urea nitrogen (BUN) test measures the same blood urea nitrogen level as the standard BUN test — a waste product from protein breakdown used to screen kidney function.
Why it's ordered: Ordered to evaluate kidney function, typically alongside creatinine, as part of routine metabolic panels or when kidney-related symptoms or risk factors are present.
What it detects: Elevated urea nitrogen can reflect reduced kidney filtration, dehydration, heart failure, or GI bleeding; the BUN-to-creatinine ratio helps distinguish a kidney cause from a non-kidney one.
Collection & prep: A standard blood draw from a vein in the arm, usually as part of a basic or comprehensive metabolic panel. No special preparation is typically required.
Results:
High – can reflect reduced kidney function, dehydration, or high protein intake
Low – less common; can reflect liver disease or malnutrition
Normal – roughly 6–24 mg/dL, though ranges vary by lab
Possible complications of kidney dysfunction: A single abnormal urea nitrogen result doesn't diagnose kidney disease on its own; it's interpreted together with creatinine and eGFR, and very high levels warrant urgent evaluation.
Statements made in the Clinical Manual have not been evaluated by the FDA. The products mentioned are not intended to diagnose, treat, cure or prevent any disease.
