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Beta-2 Microglobulin (Serum or Plasma)

Published: August 9, 2026Updated: August 16, 2026

This test measures the levels of beta-2 microglobulin, a small protein found in the blood that is produced by many types of cells, including those in the immune system and bone marrow.

Quick summary

["Beta-2 microglobulin helps assess kidney function and certain immune-related conditions."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
43819-2
Short code
B2MU
Synonyms
B2 Microglob Ur Ql
Category
chemistry
Sample
urine
Container
Sterile, preservative-free urine container; sterile container with pH stabilizer or alkalinizing agent (e.g., sodium bicarbonate) may be preferred to prevent degradation at acidic pH
Units
N/A
Ref low
0
Ref high
0.3
Fasting
false
Population
adult
Sex
all
Age range
≥ 0 years
Method
Immunoassay (e.g., Nephelometry, Chemiluminescence, or ELISA)
CPT
86386
SNOMED
313509001
Specimen volume
10 mL random urine; 24-hour collection: entire volume in a graduated container
Stability
Unstable at acidic pH (pH <6); specimen should be alkalinized or analyzed promptly. Stable for 7 days at 2-8°C when pH >6; stable for longer periods when frozen at -20°C or below.
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
24–72 hours
Order
routine

Why Is This Test Done?

Doctors may order a beta-2 microglobulin test to evaluate kidney function, especially in people with chronic kidney disease (CKD). It can also help monitor conditions like multiple myeloma, a type of blood cancer, or other disorders affecting the immune system or bone marrow. Sometimes, it’s used to check for signs of inflammation or infection.

What Does the Test Involve?

A blood sample is taken from a vein in your arm, usually in a doctor’s office or lab. The sample is sent to a lab where it is analyzed for beta-2 microglobulin levels using a specialized immunoassay or similar method.

What Are the Possible Results?

Results are typically reported as a concentration value (e.g., micrograms per deciliter, µg/dL). Your actual range may vary depending on the lab and testing method. High levels may indicate kidney problems, immune disorders, or other health conditions.

What Does It Mean If My Levels Are Abnormal?

Elevated levels of beta-2 microglobulin can signal kidney dysfunction, including reduced filtering ability, or conditions like multiple myeloma, where abnormal proteins accumulate in the blood. Lower-than-normal levels might suggest certain genetic or metabolic issues, though this is less common.

Reference range

Typically <0.3 mg/L or <0.2 mg/g creatinine in random urine samples; reference values vary by laboratory and assay method. Elevated levels may indicate proximal renal tubular dysfunction, lymphoid malignancies, or other conditions affecting tubular reabsorption.N/A

Specimen: urine

No fasting required. Patient should maintain normal hydration prior to specimen collection. First morning void or 24-hour urine collection may be preferred depending on clinical indication. Alkalinization of urine (pH >6) is recommended to prevent degradation of beta-2-microglobulin at acidic pH.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Beta-2 Microglobulin (β₂MG)

Frequently asked questions

What causes beta-2 microglobulin levels to rise?
High levels are most commonly linked to kidney disease, especially when the kidneys struggle to filter waste products effectively. It may also appear in conditions like multiple myeloma, where cancerous plasma cells produce excessive proteins, or in certain inflammatory or infectious diseases.
Can diet or lifestyle affect beta-2 microglobulin levels?
Dietary changes alone typically won’t significantly alter beta-2 microglobulin levels, but managing underlying conditions like kidney disease or multiple myeloma through diet and lifestyle (e.g., hydration, avoiding excessive protein) can help support overall health and test results.
How often should I get this test?
The frequency depends on your health status. If you have kidney disease or a condition like multiple myeloma, your doctor may recommend regular monitoring. Follow-up testing is usually scheduled based on your medical needs and treatment plan.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

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 16, 2026. · Read our editorial policy