Beta-2 microglobulin

UK laboratories print ranges such as 1.0 to 2.4 or 0.8 to 2.2 mg/L depending on the method; it rises with age and, in particular, with reduced kidney function in the general population.

Beta-2 microglobulin is a small protein found on the surface of almost every cell in the body, part of the system the immune system uses to recognise cells as self. Cells shed it continuously into the blood, and the kidneys filter it out. The level in the blood therefore rises when more cells are being turned over, as in some blood cancers, and when the kidneys are clearing it more slowly.

Doctors request it mainly in people with myeloma or lymphoma, where it is part of the standard staging tests and is followed over time, and occasionally when looking at kidney tubule damage or at the activity of some inflammatory and viral conditions.

• Reduced kidney function, the commonest reason in the general population
• Myeloma, lymphoma and chronic lymphocytic leukaemia
• Inflammatory and autoimmune conditions
• Viral infections, including HIV and hepatitis
• Older age, a little
• Some solid cancers

• Treatment of the blood condition or inflammation that raised it
• Values at the low end of the range are the usual finding in healthy young adults; a low figure is not a concern in itself
• Recovery of kidney function, for example after a transplant

• Reduced kidney function raises it without any blood condition, so it is always read with creatinine and eGFR
• It rises a little with age
• A recent viral infection raises it for a few weeks
• Methods differ between laboratories

No fasting needed. Always read alongside kidney function from the same sample. In people with a known blood condition the trend over time matters more than one value.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.