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Beta-2-Glycoprotein I-Domain 1 Antibody (IgG)
Test Code12164
CPT Codes
86146
Preferred Specimen
0.5 mL plasma collected in a 3.2% sodium citrate (light blue-top) tube
Minimum Volume
0.3 mL
Other Acceptable Specimens
Serum
Instructions
Plasma (preferred): Centrifuge light blue-top tube 15 minutes at approximately 1500 g within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial. Plasma must be free of platelets (<10,000/mcL).
Serum: Allow blood to clot (10-15 minutes) at room temperature. Centrifuge to separate serum. Pour off serum and refrigerate as soon as possible.
Serum: Allow blood to clot (10-15 minutes) at room temperature. Centrifuge to separate serum. Pour off serum and refrigerate as soon as possible.
Transport Container
Transport tube
Transport Temperature
Refrigerated (cold packs)
Specimen Stability
Room temperature: 48 hours
Refrigerated: 14 days
Frozen: 30 days
Refrigerated: 14 days
Frozen: 30 days
Methodology
Chemiluminescent Immunoassay
Setup Schedule
Set up: Tues; Report available: 3-8 days
Reference Range
| Value | Interpretation |
| <20.0 CU | Antibody not detected |
| ≥20.0 CU | Antibody detected |
Clinical Significance
Antiphospholipid syndrome (APS) is a systemic autoimmune disorder, characterized by recurrent arterial or venous thrombosis, and/or early and late miscarriages. Autoantibodies to phospholipids and to beta-2-glycoprotein 1 (B2GP1) play an important role in the pathogenesis of APS, and the measurement of these antibodies aids the diagnosis and management of the syndrome. Beta-2-glycoprotein 1, also called apolipoprotein H, is a 54 kDa glycoprotein with five domains that is present in plasma. The fifth domain contains a cluster of positively charged amino acids which is responsible for the binding to anionic phospholipids. APS patients can produce antibodies against several epitopes of the molecule. Antibodies to B2GPI are directed to one of the five domains of B2GPI, but only IgG antibodies directed to epitopes on one domain (called Domain 1 or D1) have been shown to be associated with increased risk of venous thrombosis. Even greater risk of venous thrombosis has been shown when phosphatidylserine/prothrombin antibodies are also present. This test should be used when B2GP1 IgG antibodies are present to determine whether the antibodies are directed to Domain 1. The presence of B2GPI Domain 1 antibodies should be confirmed by repeat testing at least 12 weeks apart.
