Beta-2 microglobulin (B2M) is a protein found on the surface of nearly all nucleated cells. A small amount of it is normally present in the blood, cerebrospinal fluid, and urine. The concentration in these fluids reflects the rate of cell turnover and shedding of the protein from cell surfaces. The accepted interval for serum B2M concentration generally falls between 0.8 and 2.2 milligrams per liter (mg/L), though this can vary slightly depending on the laboratory performing the test.
Monitoring B2M levels can provide valuable information regarding kidney function, as the kidneys typically filter and reabsorb this protein. Elevated levels may indicate kidney disease or certain cancers, such as multiple myeloma. Understanding these concentrations aids in diagnosing, monitoring disease progression, and evaluating the effectiveness of treatment strategies in relevant conditions. Historically, B2M has been crucial in assessing kidney transplant rejection and monitoring immune system activity.
