Beta-2 Microglobulin

• As a tumor marker: a blood B2M test may be ordered to help determine the severity and spread (stage) of multiple myeloma and may sometimes be ordered to evaluate the effectiveness of treatment. B2M has been associated with tumor burden, the amount of cancer present, and may be ordered to help evaluate the prognosis of cancers such as leukemia and lymphoma.
• In kidney disease: both blood and urine B2M tests may be ordered along with other kidney function tests such as BUN, creatinine, and microalbumin to evaluate kidney damage and disease and to distinguish between disorders that affect the glomeruli and the renal tubules. B2M tests may sometimes be ordered to monitor people who have had a kidney transplant, to detect early signs of rejection, and ordered to monitor people who are exposed to high levels of cadmium and mercury, such as with occupational exposure.
• Rarely, a CSF B2M test may be ordered to assess a disease's central nervous system involvement. The B2M test is not typically ordered to detect or monitor B2M dialysis-related amyloidosis, to monitor inflammatory conditions, or to monitor HIV.

Both blood and urine B2M tests may be ordered when a person has symptoms associated with kidney dysfunction and the doctor wants to distinguish between disorders that affect the glomeruli and the renal tubules. A urine test may also be ordered periodically to monitor a person who has had a kidney transplant and to monitor those exposed to high concentrations of cadmium or mercury.

A CSF B2M may rarely be ordered when a doctor suspects that a disease such as leukemia or lymphoma is affecting the central nervous system.

In someone with signs of kidney disease, increased levels of B2M in the blood and low levels in the urine indicate that the disorder is associated with glomeruli dysfunction. If B2M is low in the blood and high in the urine, then it is likely that the person has renal tubule damage or disease. Increases in urine B2M in a person with a kidney transplant may indicate early kidney rejection. Increases in someone who is exposed to high levels of cadmium or mercury may indicate early kidney dysfunction.

Increases in the CSF in someone with a disease such as leukemia or HIV/AIDS indicates likely central nervous system involvement.

Low levels of B2M are considered normal. B2M may be undetectable in the urine and CSF.

Drugs such as lithium, cyclosporine, cisplatin, carboplatin, and aminoglycoside antibiotics can increase B2M blood and/or urine concentrations.

Recent nuclear medicine procedures and radiographic contrast media can affect test results.