B2MC - Overview: Beta-2-Microglobulin (Beta-2-M), Spinal Fluid (2023)

Useful For

Suggests clinical disorders or settings where the test may be helpful

Evaluation of central nervous system inflammation and B-cell proliferative diseases

Method Name

A short description of the method used to perform the test


NY State Available

Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name

Lists a shorter or abbreviated version of the Published Name for a test

Beta-2-Microglobulin, CSF


Lists additional common names for a test, as an aid in searching

B2M, (Beta-2 Microglobulin), CSF Test

Beta 2 Microglobulin, CSF Test

Specimen Type

Describes the specimen type validated for testing


Specimen Required

Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Specimen Minimum Volume

Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.5 mL

Reject Due To

Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis OK

Specimen Stability Information

Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

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

Useful For

Suggests clinical disorders or settings where the test may be helpful

Evaluation of central nervous system inflammation and B-cell proliferative diseases

Clinical Information

Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

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.

Increased beta-2-M levels in the cerebrospinal fluid (CSF) have been shown to be of diagnostic use in non-Hodgkin lymphoma with central nervous system involvement. Elevated CSF:serum ratios seen in patients with aseptic meningoencephalitis suggest the possibility of neurologic processes including those associated with HIV infection and acute lymphoblastic leukemia. Beta-2-M measurement in multiple sclerosis seems to be of indeterminate usefulness.

Reference Values

Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

0.70-1.80 mcg/mL


Provides information to assist in interpretation of the test results

Elevations of cerebrospinal fluid beta-2-microgobulin levels may be seen in a number of diseases including malignancies, autoimmune disease, and neurological disorders.


Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

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

Clinical Reference

Recommendations for in-depth reading of a clinical nature

1. Koch TR, Lichtenfeld KM, Wiernik PH: Detection of central nervous system metastasis with cerebrospinal fluid beta-2-microglobulin. Cancer. 1983 Jul;52(1):101-104

2. Mavligit GM, Stuckey SE, Cabanillas FF, et al: Diagnosis of leukemia or lymphoma in the central nervous system by beta-2-microglobulin determination. N Engl J Med. 1980 Sep 25;303(13):718-722

3. Jeffery GM, Frampton CM, Legge HM, Hart DN: Cerebrospinal fluid beta 2-microglobulin levels in meningeal involvement by malignancy. Pathology. 1990 Jan;22(1):20-23

4. Us O, Lolli F, Baig S, Link H: Intrathecal synthesis of beta-2-microglobulin in multiple sclerosis and aseptic meningo-encephalitis. Acta Neurol Scand. 1989 Dec;80(6):598-602

5. Elovaara I, Livanainen M, Poutianen E, et al: CSF and serum beta-2-microglobulin in HIV infection related to neurological dysfunction. Acta Neurol Scand. 1989 Feb;79(2):81-87

6. 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

7. Brew BJ, Bhalla RB, Fleisher M, et al: Cerebrospinal fluid beta 2 microglobulin in patients infected with human immunodeficiency virus. Neurology. 1989 Jun;39(6):830-834

8. Musto P, Tomasi P, Cascavilla N, et al: Significance and limits of cerebrospinal fluid beta-2-microglobulin measurement in course of acute lymphoblastic leukemia. Am J Hematol. 1988 Aug;28(4):213-218

9. Lucey DR, McGuire SA, Clerici M, et al: Comparison of spinal fluid beta 2-microglobulin levels with CD4+ T cell count, in vitro T helper cell function, and spinal fluid IgG parameters in 163 neurologically normal adults infected with the human immunodeficiency virus type l. J Infect Dis. 1991 May;163(5):971-975

10. Bjerrum OW, Bach FW, Zeeberg I: Increased level of cerebrospinal fluid beta 2-microglobulin is related to neurologic impairment in multiple sclerosis. Acta Neurol Scand. 1988 Jul;78(1):72-75

11. 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

Method Description

Describes how the test is performed and provides a method-specific reference

In this Siemens Nephelometer II method, the light scattered onto the antigen-antibody complexes is measured. The intensity of the measured scattered light is proportional to the amount of antigen-antibody complexes in the sample under certain conditions. If the antibody volume is kept constant, the signal behaves proportionally to the antigen volume. A reference curve is generated by a standard with a known antigen content on which the scattered light signals of the samples can be evaluated and calculated as an antigen concentration. Antigen-antibody complexes are formed when a sample containing antigen and the corresponding antiserum are put into a cuvette. A light beam is generated with a light emitting diode, which is transmitted through the cuvette. The light is scattered onto the immuno-complexes that are present. Antigen and antibody are mixed in the initial measurement, but no complex is formed yet. An antigen-antibody complex is formed in the final measurement. The result is calculated by subtracting the value of the final measurement from the initial measurement. The distribution of intensity of the scattered light depends on the ratio of the particle size of the antigen-antibody complexes to the radiated wavelength.(Instruction manual: Siemens Nephelometer II, Siemens, Inc.; Version 3, 2008; Addendum to the Instruction Manual 2.3, 08/2017)

PDF Report

Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed

Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available

The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

Same day/1 to 2 days

Specimen Retention Time

Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

14 days

Performing Laboratory Location

Indicates the location of the laboratory that performs the test



Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their account representative. For assistance, contact Customer Service.

Test Classification

Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information

Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
B2MC Beta-2-Microglobulin, CSF 1951-3
Result Id Test Result Name Result LOINC Value

Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.

B2MC Beta-2-Microglobulin, CSF 1951-3


What does it mean when your beta-2 microglobulin is high? ›

The higher your B2M levels, the more cancer you have in your body. Higher levels are linked to cancers that tend to grow faster./li> If you have multiple myeloma, higher levels of B2M are linked with kidney problems.

What is normal range for beta-2 microglobulin CSF? ›

Urine beta2 microglobulin values indicate renal filtration disorders. Measurement of values in both serum and urine can help distinguish a problem of cellular activation from a renal disorder. Normal findings : Blood: 0.70-1.80 mcg/mL.

What is beta-2 microglobulin B2M indicative in case of? ›

The beta-2 microglobulin (B2M) test may be used when known physical or suspected kidney damage occurs to distinguish between glomerular and tubular disorders of the kidney.

What does beta-2 microglobulin indicate? ›

A small protein normally found on the surface of many cells, including lymphocytes, and in small amounts in the blood and urine. An increased amount in the blood or urine may be a sign of certain diseases, including some types of cancer, such as multiple myeloma or lymphoma.

What is the prognosis for beta 2 microglobulin myeloma? ›

Beta 2 microglobulin is a low molecular weight protein found on the surface of all nucleated cells: it is the light chain of the HL-A histocompatibility complex. The increased levels of serum beta 2 microglobulin in patients with multiple myeloma have been associated with a poor prognosis.

What is the beta 2 microglobulin level for multiple myeloma? ›

The International Staging System for Multiple Myeloma

Stage 1 – Serum beta-2 microglobulin level measuring less than 3.5 (mg/L) with an albumin level measuring 3.5 (g/dL) or greater.

When do you suspect multiple myeloma? ›

It's often only suspected or diagnosed after a routine blood or urine test. However, myeloma will eventually cause a wide range of problems, including: a persistent dull ache or specific areas of tenderness in your bones. weak bones that break (fracture) easily.

What is the prognosis for beta-2 microglobulin lymphoma? ›

Results: The complete remission rate for patients with a beta-2M level of 3.0 mg/L or greater was 36% compared with 71% for those with a level of less than 3.0 mg/L. Using multivariate analysis that tested beta-2M as a continuous variable, it was selected as the most significant factor for complete response.

How do you detect multiple myeloma? ›

Bone marrow biopsy

This test is required to confirm the diagnosis of multiple myeloma. A needle is inserted into the bone marrow space to remove a small sliver of bone marrow. Our hematopathologists examine the tissue under a microscope to determine if there are myeloma cells in the bone marrow.

What are the symptoms of beta-2 microglobulin amyloidosis? ›

Dialysis-related beta2-microglobulin amyloidosis usually affects the bones and joints. Initial symptoms include carpal tunnel syndrome, shoulder pain and inflammation of the tendon sheaths of the hands. Case reports of severe pulmonary hypertension and heart failure also exist.

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