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Beta-2-glycoprotein I (Protein S) Antigen

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

This test measures the amount of a specific protein, Beta-2-glycoprotein I, in your blood. It helps assess certain blood-related conditions.

Quick summary

["This test may help diagnose or monitor autoimmune disorders or blood clotting risks."]

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

Key facts at a glance

LOINC
44449-7
Short code
B2 Glycoprot1 IgM SerPl IA-aCnc
Synonyms
B2 Glycoprot1 IgM SerPl IA-aCnc
Category
glucose
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
82784
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms or risk factors for autoimmune diseases, such as lupus or antiphospholipid syndrome, or if you have unexplained blood clots or bleeding issues. It may also be used to monitor treatment progress or check for genetic conditions affecting protein levels.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the blood draw if instructed by your provider. Bring any medications you’re currently taking to your appointment.

How the Test Works

A small sample of blood is taken from a vein in your arm. The blood is then processed to measure the protein levels using a specialized immunoassay method. This helps detect or quantify the protein for further evaluation.

Possible Results and Next Steps

Results may be compared to standard reference ranges to identify deviations. If your levels are unusually high or low, your provider will discuss next steps, which could include additional testing, lifestyle adjustments, or treatment planning.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormal levels of Beta-2-glycoprotein I may indicate underlying autoimmune conditions, such as lupus or thrombophilia (increased clotting risk). Low levels could suggest genetic disorders or liver/kidney dysfunction. Regular monitoring may be needed if you have a history of clotting disorders or autoimmune diseases.

Short name

Beta-2-Glycoprotein I (Protein S) Level

Frequently asked questions

What does a normal result mean?
A normal result means your protein levels fall within expected ranges for your age and health. However, this test alone may not diagnose a condition—your provider will consider your full medical history and other test results.
Can diet or medications affect this test?
Some medications (like blood thinners or steroids) or certain foods may influence protein levels, but your provider will guide you on any necessary adjustments. Avoiding alcohol or certain supplements before testing can help ensure accurate results.
How often should I get this test?
Frequency depends on your health status. If you have a known condition (e.g., lupus or clotting disorder), your provider may recommend periodic testing. Follow-up schedules are tailored to your individual needs.
  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