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Beta-2 Microglobulin (Serum)

Published: July 27, 2026Updated: August 25, 2026

Beta-2 microglobulin (B2M) is a protein found on the surface of most nucleated cells and is shed into the blood, making it useful for assessing kidney function.

Quick summary

Beta-2 microglobulin is a diagnostic biomarker for evaluating kidney function.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
μg/mL
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche Beta-2-Microglobulin, Abbott Beta-2-Microglobulin
interpretation: {"text":"B2M levels within the range of 0.7–1.8 μg/mL suggest normal kidney function.","label":"Normal"}; {"text":"Levels above 1.8 μg/mL may indicate impaired kidney function or other conditions such as multiple myeloma or HIV infection.","label":"Elevated"}

Beta-2 microglobulin (B2M) is a small protein that is a component of the major histocompatibility complex (MHC) class I molecules and is present on the surface of nearly all nucleated cells. It is shed into the bloodstream and filtered by the kidneys, where it is normally reabsorbed and metabolized.

In conditions where kidney function is impaired, the levels of B2M in the blood can rise due to decreased filtration and clearance. This makes it a valuable biomarker for diagnosing and monitoring renal diseases.

The reference range for serum B2M is typically between 0.7 and 1.8 μg/mL. Elevated levels may indicate renal dysfunction, while lower levels are less common and may be associated with certain immunological conditions.

Frequently asked questions

What conditions can cause elevated B2M levels?
Elevated B2M levels can be caused by renal dysfunction, inflammation, certain cancers like multiple myeloma, and viral infections such as HIV.
How is the B2M test performed?
The B2M test involves a simple blood draw, and the sample is analyzed in a laboratory to measure the concentration of beta-2 microglobulin in the serum.
  1. 1
    Beta-2 Microglobulin - Lab Tests OnlineSource
  2. 2
    Beta-2 Microglobulin Test - MedlinePlusSource

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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy