Test guide
BUN (Blood Urea Nitrogen)
A BUN, or blood urea nitrogen test, measures the amount of urea nitrogen in your blood. Urea nitrogen is a waste product that forms as your body breaks down proteins. It's carried in your blood and then removed by your kidneys when you urinate (pee).
What it is for
A BUN test is often part of a series of tests called a comprehensive metabolic panel (CMP). It can help diagnose or monitor kidney diseases. Source: MedlinePlus, National Library of Medicine. Medical test information is public domain. Source identity and definition checked automatically on 2026-10-18. No individual clinical interpretation or human reviewer is asserted.
Limitations
Reference intervals and interpretation depend on the laboratory, specimen, method and clinical context. This source definition is educational information; it does not establish a diagnosis, product approval or suitability for an individual.
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