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Epic Code LAB49 Beta-2-Microglobulin, Serum

Additional Codes

Mayo Code: B2M

Epic Code: LAB49

Interface Order Alias: 10093

Cerner code: 8178

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Prognosis assessment of multiple myeloma


Evaluation of renal tubular disorders

Specimen Type


Specimen Required

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Laboratory Test Directory Note:

COLLECTION NOTE: Volumes listed are in serum or plasma, draw approximately 2 1/2 times the requested volume in whole blood.

Specimen Minimum Volume

0.5 mL


If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-General Request (T239)

-Renal Diagnostics Test Request (T830)

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  14 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK


Results determined by assays using different manufacturers or methods may not be comparable

Clinical Information

Beta-2-microglobulin (beta-2-M) is a small membrane protein (11,800 Da) associated with the heavy chains of class I major histocompatibility complex proteins and is, therefore, on the surface of all nucleated cells. The small size allows beta-2-M to pass through the glomerular membrane, but it is almost completely reabsorbed in the proximal tubules.


Serum beta-2-M levels are elevated in diseases associated with increased cell turnover. Levels are also elevated in several benign conditions such as chronic inflammation, liver disease, kidney dysfunction, some acute viral infections, and a number of malignancies, especially hematologic malignancies associated with the B-lymphocyte lineage.


In multiple myeloma, beta-2-M is a powerful prognostic factor, and values less than4 mcg/mL are considered a good prognostic factor.


In renal tubular disease, serum levels are low and urine levels are high. Although urine beta-2-M has been used to assess tubular dysfunction, it is not stable in urine below pH 5.5.


See Multiple Myeloma: Laboratory Screening

Method Name


Report Available

Same day/1 to 2 days

Reporting Name

Beta-2-Microglobulin, S

Reference Values

1.21-2.70 mcg/mL


A serum beta-2-microglobulin (beta-2-M) value of less than 4 mcg/mL is a good prognostic factor in patients with multiple myeloma. In a study of pretreatment serum beta-2-M levels in 100 patients with myeloma, it was reported that the median survival of patients with values greater than 4 mcg/mL was 12 months, whereas median survival for patients with values less than 4 mcg/mL was 43 months.

Method Description

Concentrations of beta-2-microglobulin are determined by nephelometry.(Instruction manual: Siemens Nephelometer II Operations. Siemens, Inc., Newark, DE)

Day(s) Performed

Monday through Friday

Clinical Reference

1. Bataille R, Magub M, Grenier J, Donnadio D, Sany J: Serum beta-2-microglobulin in multiple myeloma: Relation to presenting features and clinical status. Eur J Cancer Clin Oncol. 1982 Jan;18(1):59-66

2. Garewal H, Durie BG, Kyle RA, Finley P, Bower B, Serokman R: Serum beta-2-microglobulin in the initial staging and subsequent monitoring of monoclonal plasma cell disorders. J Clin Oncol. 1984 Jan;2(1):51-57

3. Norfolk D, Child JA, Cooper EH, Kerruish S, Ward AM: Serum beta-2-microglobulin in myelomatosis: potential value in stratification and monitoring. Br J Cancer. 1980 Oct;42(4):510-550

4. Dolan MJ, Lucey DR, Hendrix CW, Melcher GP, Spencer GA, Boswell RN: Early markers of HIV infection and subclinical disease progression. Vaccine. 1993;11(5):548-551

5. Karlsson FA, Wibell L, Evrin PE: Beta-2-microglobulin in clinical medicine. Scand J Clin Lab Invest. 1986;154:27-37

6. Greipp PR, Katzmann JA, O'Fallon WM, Kyle RA: Value of beta-2-microglobulin level and plasma cell labeling indices as prognostic factors in patients with newly diagnosed myeloma. Blood. 1988 Jul;72(1):219-223

7. Dietzen DJ, Willrich MAV: Amino acids, peptides, and proteins. In: Rifai N, Chiu RWK, Young I, Burnham CAD, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier; 2023:chap 31

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
B2M Beta-2-Microglobulin, S 1952-1


Result ID Test Result Name Result LOINC Value
B2M Beta-2-Microglobulin, S 1952-1