Beta-2-Microglobulin
This test measures the amount of beta-2-microglobulin, a small protein found in your blood that helps transport molecules across cell membranes. It is often checked in connection with kidney function or certain immune-related conditions.
["Beta-2-microglobulin helps assess kidney function and immune system health."]
Key facts at a glance
- LOINC
- 1953-9
- Short code
- B2MU
- Synonyms
- B2 Microglob Ur-mCnc
- Category
- chemistry
- Sample
- urine
- Container
- Sterile, preservative-free urine collection container
- Units
- N/A
- Ref low
- 0
- Ref high
- 0.3
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunoassay (chemiluminescent or nephelometric)
- CPT
- 86337
- SNOMED
- 313810002
- Specimen volume
- 10 mL of random or 24-hour urine
- Stability
- Stable for 24 hours at room temperature (20-25°C); up to 7 days refrigerated at 2-8°C; up to 3 months frozen at -20°C. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may order a beta-2-microglobulin test if you have symptoms like fatigue, muscle weakness, or joint pain that could indicate kidney problems or conditions affecting the immune system. It may also be used to monitor kidney transplant patients or those with certain blood disorders.
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast for a few hours before the blood draw, but this depends on your healthcare provider’s instructions. Bring any medications you’re currently taking to your appointment.
What the Test Involves
A small needle will be used to draw blood from a vein in your arm. The process is quick and typically causes minimal discomfort. You may feel a slight pinch or sting, but most people tolerate it well.
What the Results Mean
Results are not typically interpreted alone but are often reviewed alongside other tests and your medical history. Elevated levels may suggest kidney disease, immune disorders, or other conditions affecting protein metabolism.
Reference range
< 0.3 mg/L (or < 300 µg/L) in random urine; < 0.2 mg/g creatinine in spot urine when normalized to creatinineN/A
No fasting required. Patient should maintain normal hydration status. Avoid strenuous exercise prior to collection as it may transiently affect results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Beta-2-Microglobulin Level
Frequently asked questions
What causes beta-2-microglobulin levels to be higher than usual?
What causes beta-2-microglobulin levels to be lower than usual?
How often should I get this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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