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Test Code B2M Beta-2-Microglobulin (Beta-2-M), Serum

Reporting Name

Beta-2-Microglobulin, S

Useful For

Prognosis assessment of multiple myeloma


Evaluation of renal tubular disorders

Testing Algorithm

See Laboratory Screening Tests for Suspected Multiple Myeloma in Special Instructions.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type


Specimen Required


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 1 mL

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

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

Reference Values

1.21-2.70 mcg/mL

Day(s) and Time(s) Performed

Monday through Saturday; 3 p.m.

Test Classification

This test has been cleared or approved by the U.S. 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

Clinical Information

Beta-2-microglobulin (beta-2-M) is a small membrane protein (11,800 Dalton) 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, renal 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 <4 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 Laboratory Screening Tests for Suspected Multiple Myeloma in Special Instructions.


Serum beta-2-microglobulin (beta-2-M) <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 >4 mcg/mL was 12 months, whereas median survival for patients with values <4 mcg/mL was 43 months.

Clinical Reference

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

2. Garewal H, Durie BG, Kyle RA, et al: Serum beta-2-microglobulin in the initial staging and subsequent monitoring of monoclonal plasma cell disorders. J Clin Oncol 1984;2:51-57

3. Norfolk D, Child JA, Cooper EH, et al: Serum beta-2-microglobulin in myelomatosis: potential value in stratification and monitoring. Br J Cancer 1980;42:510-550

4. Dolan MJ, Lucey DR, Hendrix CW, et al: Early markers of HIV infection and subclinical disease progression. Vaccine 1993;11:548-551

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;72:219-223

Analytic Time

Same day/1 day

Reject Due To


Mild OK; Gross OK


Mild OK; Gross reject


Mild OK; Gross OK



Method Name



If not ordering electronically, complete, print, and send a General Request Form (T239) with the specimen (