Beta-2 Microglobulin (B2M) Tumor Marker Test
Reviewed
This test measures the amount of beta-2 microglobulin (B2M) protein in your body fluids. B2M is a tumor marker often used after a diagnosis of certain blood or bone marrow cancers to help determine how much the cancer has grown or spread, predict its progression, choose treatment, and monitor whether treatment is working. High levels can also be caused by noncancerous conditions such as kidney disease or autoimmune disorders. This test is not used to screen for or diagnose cancer.
Preparation and collection
For blood and urine tests, no special preparations are needed. For a CSF analysis (spinal tap), you may be asked to empty your bladder and bowels before the test.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- This test is not used to screen for or diagnose cancer.
- High B2M levels can be caused by many noncancerous conditions, including kidney disease, HIV, and multiple sclerosis.
- Results must be interpreted by a healthcare professional in the context of your full medical history and other tests.
What to do next
If you have questions about your test results, talk with your provider. They can explain what your B2M levels mean for your specific situation and treatment plan.
Evidence source
U.S. National Library of Medicine: Beta-2 Microglobulin (B2M) Tumor Marker Test