The Beta-2 Microglobulin test measures a protein shed from the surface of your cells, particularly immune cells. This test is a vital prognostic marker used by doctors to manage and monitor certain blood cancers, such as Multiple Myeloma and some lymphomas. The level of this protein helps your doctor understand the extent (stage) of the condition and monitor how well your body is responding to treatment. It is also an important test for assessing kidney function. This simple blood test provides your care team with the critical, actionable data needed to guide your treatment plan effectively.