B2-Glycoprotein I (Protein S) Antibody, Serum
This test measures the presence of antibodies against B2-glycoprotein I, a protein involved in blood clotting regulation. It helps assess risks related to blood clots or autoimmune conditions.
["This test may help evaluate clotting disorders or autoimmune conditions by checking for immune system responses to a specific protein."]
Key facts at a glance
- LOINC
- 40456-6
- Short code
- B2 Glycoprot1 Ab Ser-aCnc
- Synonyms
- B2 Glycoprot1 Ab Ser-aCnc
- Category
- glucose
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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 Is Done
Your doctor may order this test if you have symptoms like unexplained bruising, blood clots, or signs of autoimmune diseases. It can also be part of a broader evaluation for conditions affecting blood clotting or immune function.
What to Expect Before the Test
No special preparation is needed. You may have a blood sample drawn from a vein in your arm, similar to other blood tests. Wear comfortable clothing if you need an arm sleeve removed.
What the Test Results Mean
Positive results indicate the presence of antibodies against B2-glycoprotein I, which may suggest an autoimmune response. The exact meaning depends on your symptoms and medical history. Your doctor will interpret results in the context of your overall health.
Common Conditions Linked to This Test
This test is often linked to conditions like antiphospholipid syndrome (APS), a disorder causing blood clots or pregnancy complications. It may also be relevant in diagnosing or monitoring autoimmune diseases.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
B2-glycoprotein I is a cofactor in blood clotting pathways. Antibodies against it can interfere with normal clotting processes, increasing the risk of clots or bleeding disorders. This test helps identify patients at risk for autoimmune-related clotting issues or other systemic conditions.
Short name
Protein S Antibody (Serum)
Frequently asked questions
What does a positive test result mean?
How often should I get this test?
Can lifestyle changes affect this test result?
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