Test guide
Beta 2 Microglobulin (B2M) Tumor Marker Test
A beta-2 microglobulin tumor marker test measures the amount of a protein called beta-2 microglobulin (B2M) in your body fluids. The test usually uses a sample of your blood. It may also be done using urine (pee) or in rare cases cerebrospinal fluid (CSF).
What it is for
Though a beta-2 microglobulin tumor marker test cannot be used to screen for or diagnose cancer, it can provide valuable information about any bone marrow or blood cancer you already have. For example, testing your B2M levels can help your provider: 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.
Also known as
- total beta-2 microglobulin, β2-microglobulin, B2M, B2MG, thymotaxin
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