beta2-microglobulin (B2M) test, a test that analyzes blood, urine, or fluid for increased levels of B2M, a protein found on the surface of all cells. Increased levels in the urine indicate renal tubule disease; drug-induced renal toxicity; heavy metal–induced renal disease; lymphomas, leukemia, or myeloma; or AIDS. Increased serum levels indicate lymphomas, leukemia, or myeloma; glomerular renal disease; renal transplant rejection; viral infections, especially HIV and cytomegalovirus; or chronic inflammatory processes.
