Beta 2 Microglobulin (B2M) Tumor Marker Test Test
This test measures the amount of beta-2 microglobulin (B2M) protein in your blood, urine, or cerebrospinal fluid. High levels can be a sign of certain blood cancers, but the test is not used to diagnose cancer. Instead, it helps monitor cancers like multiple myeloma, chronic lymphocytic leukemia, and lymphoma after diagnosis.
What this test measures
The test measures the amount of beta-2 microglobulin (B2M) protein in body fluids, usually blood, but sometimes urine or cerebrospinal fluid. B2M is a small protein on cell surfaces that is released when cells are damaged or grow quickly. Normally, kidneys filter it out, so only small amounts are present in healthy people.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
Higher B2M levels mean more cancer in the body and are linked to faster-growing cancers. In multiple myeloma, higher levels are often linked to kidney problems.
Frequently asked questions
What is a beta-2 microglobulin tumor marker test?
It measures the amount of B2M protein in your blood, urine, or cerebrospinal fluid. B2M is a protein on cell surfaces that can be released in higher amounts by certain cancers.
Can this test diagnose cancer?
No. According to MedlinePlus, healthcare providers do not use this test to diagnose cancer because high levels can be caused by many conditions.
What cancers are associated with high B2M levels?
High levels are often caused by blood and bone marrow cancers such as multiple myeloma, chronic lymphocytic leukemia (CLL), and certain types of lymphoma.
What noncancerous conditions can raise B2M levels?
Kidney disease and autoimmune disorders can cause high B2M levels.
How are B2M test results used to monitor treatment?
If B2M levels decrease during treatment, it may mean the treatment is working. If levels increase, the treatment may not be working. Stable levels may mean the disease is stable.
Related lab tests
Sources
- MedlinePlus: Beta 2 Microglobulin (B2M) Tumor Marker Test — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.