Beta-2 Microglobulin Kidney Disease
- Also Known As:
- B2M
- β2-Microglobulin
- Thymotaxin
- Formal Name:
- Beta2 Microglobulin
- Serum or Urine

This page was fact checked by our expert Medical Review Board for accuracy and objectivity. Read more about our editorial policy and review process.
At a Glance
Why Get Tested?
To help detect kidney damage and follow kidney disorders; sometimes to monitor people who are exposed to cadmium
When To Get Tested?
When you have symptoms and signs associated with kidney dysfunction; periodically if you work with cadmium
Sample Required?
A blood sample drawn from a vein in your arm; sometimes a random or 24-hour urine sample
Test Preparation Needed?
None
You may be able to find your test results on your laboratory’s website or patient portal. However, you are currently at Testing.com. You may have been directed here by your lab’s website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab’s website or portal, or contact your healthcare practitioner in order to obtain your test results.
Testing.com is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.
The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.
If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.
Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called “normal” values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.
While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are “within normal limits.”
For more information, please read the article Reference Ranges and What They Mean.
What is being tested?
Beta-2 microglobulin (B2M) is a protein that is found on the surface of nucleated cells (contain a nucleus) and functions as part of the human immune system. This protein is routinely shed by cells into the blood and is present in most body fluids, with highest levels in the blood, generally lower levels in spinal fluid, and trace levels in urine.
In the kidneys, B2M passes through blood-filtering units called the glomeruli and is then reabsorbed by the renal proximal tubules, structures that reclaim water, proteins, vitamins, minerals, and other vital substances. Normally, only small amounts of B2M are present in the urine, but when the renal tubules become damaged or diseased, B2M concentrations increase due to the decreased ability to reabsorb this protein. When the glomeruli in the kidneys are damaged, they are unable to filter out B2M, so the level in the blood rises.
Common Questions
View Sources
Sources Used in Current Review
2017 review performed by Rita Khoury, MD, DABCC, FACB, Laboratory Director, Aculabs, Inc.
Surovi Hazarika, Brian H. Annex. (2017) Biomarkers and Genetics in Peripheral Artery Disease. Clinical Chemistry Jan 2017, 63 (1) 236-244.
Giuseppe Coppolino, Davide Bolignano, Laura Rivoli, et al. (2014) Tumour Markers and Kidney Function: A Systematic Review. BioMed Research International Volume 2014 (2014), Article ID 647541, 9 pages.
Sedighi O, Abediankenari S, Omranifar B. (2015) Association Between Plasma Beta-2 Microglobulin Level and Cardiac Performance in Patients With Chronic Kidney Disease. Nephro-urology Monthly. 2015;7(1):e23563. doi:10.5812/numonthly.23563.
Zeng X, Hossain D, Bostwick DG, Herrera GA, Ballester B, et al. (2014) Urinary β2-Microglobulin is a Sensitive Indicator for Renal Tubular Injury. SAJ Case Rep 1: 103. doi: 10.18875/2375-7043.1.103.
Anita Basu, MD, FACP; Vecihi Batuman, MD, FASNl Reynaldo Matute, MD, et al. (2017) Dialysis-Related Beta-2m Amyloidosis. Available online at http://emedicine.medscape.com/article/246542-overview. Accessed May 2017.
Sources Used in Previous Reviews
Pagana, K. D. & Pagana, T. J. (© 2007). Mosby’s Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 155-156.
Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 742-743.
Basu, A. et. al. (Updated 2008 February 22). Amyloidosis, Beta2M (Dialysis-Related) eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/246542-overview. Accessed August 2009.
Holmes, R. et. al. (Updated: 2009 July 30). Amyloidosis, Overview. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/335414-overview. Accessed August 2009.
(Updated 2008 September). Renal Function Markers – Kidney Disease. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/RenalDz/RenalFunctionMarkers.html?client_ID=LTD. Accessed August 2009.
(© 1995–2009). Overview: Beta-2 Microglobulin (B[2]-M), Urine. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/300243. Accessed August 2009.
(© 1995–2009). Overview: Beta-2-Microglobulin (Beta-2-M), Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/9234. Accessed August 2009.
(2006 May). Amyloidosis and Kidney Disease. National Kidney and Urologic Diseases Information Clearinghouse [On-line information]. Available online at http://kidney.niddk.nih.gov/kudiseases/pubs/amyloidosis/. Accessed August 2009.
Basu, A. et. al. (Updated 2012 August 2). Dialysis-Related Beta-2m Amyloidosis. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/246542-overview. Accessed June 2013.
Gooptu, M. and Scarpaci, A. (Updated 2012 April 6). Beta2-Microglobulin. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/2086864-overview. Accessed June 2013.
Beta-2-Microglobulin (Beta-2-M), Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/9234. Accessed June 2013.
Liabeuf, S. (2012 August 15). Plasma beta-2 microglobulin is associated with cardiovascular disease in uremic patients. Kidney International (2012) 82, 1297–1303 Abstract [On-line information]. Available online at http://www.nature.com/ki/journal/v82/n12/abs/ki2012301a.html. Accessed June 2013.
(Updated 2010 September 9). Amyloidosis and Kidney Disease. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) [On-line information]. Available online at http://kidney.niddk.nih.gov/kudiseases/pubs/amyloidosis/. Accessed June 2013.
Winchester, J. (2005 July). Novel Changes in Beta2-Microglobulin in Dialysis Patients. Clinical Chemistry v 51 (7) 1089-1090 [On-line information]. Available online at http://www.clinchem.org/content/51/7/1089.full. Accessed June 2013.
Pagana, K. D. & Pagana, T. J. (© 2011). Mosby’s Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 680-682.
Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER, Bruns DE, eds. 4th edition, St. Louis: Elsevier Saunders; 2006, pg 555.
Rao LV, Pechet L, Jenkins A, et al. Laboratory tests, in Wallach’s Interpretation of Diagnostic Tests, 9th ed. (2011) Williamson MA, Snyder ML, eds. Lippincott Williams & Wilkins. Chapter 2.
Ask a Laboratory Scientist
