Beta-2 microglobulin (B2M) is a protein that is found on the surface (part of MHC class I) of almost all cells in the body and is shed by cells into the blood, particularly by B lymphocytes and tumour cells. It is present in most body fluids and its concentration in the bloodstream rises with conditions that increase cell production and/or destruction, or that activate the immune system. This test measures B2M in the blood, urine,…Beta-2 microglobulin (B2M) is a protein that is found on the surface (part of MHC class I) of almost all cells in the body and is shed by cells into the blood, particularly by B lymphocytes and tumour cells. It is present in most body fluids and its concentration in the bloodstream 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, with inflammatory disorders and infections (e.g., HIV, CMV) and in kidney disease. It is useful as a tumour marker because it provides prognostic information in blood cell cancers. Though it can be used to assess kidney function, this article focuses on its use as a tumour marker. The B2M concentration can be increased in the CSF of individuals with blood cell cancers that have spread (metastasised) 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. Is any test preparation needed to ensure the quality of the sample? No test preparation is needed See MoreSee Less
