At a glance
Also known as
B2MG; B2M; B2Microglobulin; β2-Microglobulin; Thymotaxin
Why get tested?
To help evaluate the severity and of multiple myeloma, leukaemia, or lymphoma; to distinguish between kidney disorders; to detect kidney damage; and sometimes to monitor people who are exposed to cadmium.
When to get tested?
When you have been diagnosed with multiple myeloma or certain other cancers; sometimes to monitor disease activity and treatment; when you have signs associated with kidney dysfunction; periodically if you work with cadimum.
A blood sample drawn from a vein in your arm; sometimes a random or ; rarely, a sample
Test preparation needed?
What is being tested?
Beta-2-microglobulin (B2M) is a 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 tumour 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 .
B2M is frequently elevated in the blood with cancers such as multiple myeloma, leukaemia and lymphoma, with inflammatory disorders, infections (e.g. HIV, CMV) and in kidney disease. Because B2M is increased with blood cell cancers, it may be useful as a tumour marker. Though it can also be used to assess kidney function.
In the kidneys, B2M passes through blood filtering units, the , and is then reabsorbed by the - these are structures that reclaim water, proteins, vitamins, minerals and other substances that are useful to the body. Normally, only small amounts of B2M are present in the urine but when the renal tubules become damaged or diseased, concentrations increase due to the decreased ability of the tubules to reabsorb this protein. When the glomeruli in the kidneys are damaged, then they are unable to filter out B2M, so the level in the blood rises. In people with kidney disease who are undergoing , B2M can form long protein chains that can be deposited in joints and tissues, causing stiffness and pain. This condition is called B2M dialysis-associated amyloidosis.
B2M levels can be increased in the CSF of individuals with blood cell cancers that have spread (metastasised) to the brain, such as leukaemia and lymphoma, but also with some 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. Urine can be collected as a random sample or a . Rarely, a sample can be collected by a doctor from the lower back using a procedure called a or spinal tap.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed