What is a beta-2 microglobulin tumor marker test?This test measures the amount of a protein called beta-2 microglobulin (B2M) in the blood, urine, or cerebrospinal fluid (CSF). B2M is a type of tumor marker. Tumor markers are substances made by cancer cells or by normal cells in response to cancer in the body.B2M is found on the surface of many cells and is released into the body. Healthy people have small amounts of B2M in their blood and urine.People with cancers of the bone marrow and blood often have high levels of B2M in their blood or urine. These cancers include multiple myeloma, lymphoma, and leukemia.High levels of B2M in cerebrospinal fluid can mean that cancer has spread to the brain and/or spinal cord.A B2M tumor marker test is not used to diagnose cancer. But it can provide important information about your cancer, including how serious it is and how it may develop in the future.Other names: total beta-2 microglobulin, β2-microglobulin, B2M
