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Beta-2 Microglobulin Tumor Marker

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Also known as: B2M; B2M; β2-Microglobulin; Thymotaxin
Formal name: Beta2 Microglobulin, Serum, Urine, or CSF

Were you looking for the Beta-2 Microglobulin test that is ordered to evaluate kidney disease?

The Test Sample

What is being tested?

Beta-2 microglobulin (B2M) is a protein that is found on the surface of almost all cells in the body and is shed by cells into the blood, particularly by B lymphocytes and tumor cells. It is present in most body fluids and its level rises with conditions that increase cell production and/or destruction, or that activate the immune system. This test measures B2M in the blood, urine, or rarely in the cerebrospinal fluid (CSF).

B2M is frequently elevated in the blood with cancers such as multiple myeloma and lymphoma and with inflammatory disorders and infections (e.g., HIV, CMV). Because B2M is increased with blood cell cancers, it is useful as a tumor marker. Though it can be used to assess kidney function, this article focuses on its use as a tumor marker.

The B2M level can be increased in the CSF of individuals with blood cell cancers that have spread (metastasized) to the brain, such as lymphoma, but also with some chronic disorders such as multiple sclerosis and with viral infections such as HIV.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm. A 24-hour urine sample may also be collected. Rarely, a CSF sample may be collected from the lower back using a procedure called a lumbar puncture or spinal tap.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.