|
|
| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
Beta-2-Glycoprotein I Antibody (IgG) with Reflex to B2GPI-Domain 1
Test Code12163
CPT Codes
86146
Includes
If Beta-2-Glycoprotein I Antibody (IgG) is ≥20.0, then Beta-2-Glycoprotein I-Domain 1 Antibody (IgG) will be performed at an additional charge (CPT code(s): 86146).
Preferred Specimen
3 mL plasma collected in a 3.2% sodium citrate (light blue-top) tube
Minimum Volume
1.5 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
Refrigrated (cold packs)
Specimen Stability
Room temperature: 48 hours
refrigerated: 14 days
Frozen: 30 days
refrigerated: 14 days
Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gross hemolysis • Grossly lipemic
Methodology
Immunoassay (IA)
Setup Schedule
Set up: Mon-Sat; Report available: 4-9 days
Reference Range
| Value | Interpretation |
| <20.0 U/mL | Antibody not detected |
| ≥20.0 U/mL | Antibody detected |
Clinical Significance
The antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized venous and/or arterial thrombosis (intravascular blood clotting), thrombocytopenia, recurrent fetal loss, and moderate-to-high titers of antiphospholipid (aPL) antibodies, lupus anticoagulant (LA), anti-cardiolipin (aCL) antibodies and anti-Beta-2-glycoprotein I (aB2GPI) antibodies.
aPL antibodies are autoantibodies that react with negatively charged phospholipids (e.g. Cardiolipin). They are frequently found in sera of patients with systemic lupus erythematosus (SLE) and related diseases and are typical for the development of secondary APS. The presence of antiphospholipid antibodies in patients with no other autoimmune diseases is characteristic of primary APS. Because aCL antibodies are found in 80-90% of patients with APS, this test is very sensitive for the diagnosis of the syndrome. However, the aCL test is not specific to APS because aCL antibodies can also be detected in other autoimmune diseases, following administration of several drugs, and in the aftermath of infectious diseases (e.g., syphilis, hepatitis C and infectious mononucleosis).
B2GPI, also known as apolipoprotein H, is a 54 kDa serum cofactor (protein) that inhibits the intrinsic coagulation pathway and is involved in the regulation of blood coagulation. Detailed investigations about the nature of the cardiolipin-B2GPI complex have shown that B2GPI is the real autoantigen of anti-cardiolipin antibodies. In addition to being a prerequisite for binding to anti-cardiolipin antibodies, B2GPI has been identified as the primary antigen for these antibodies. Hence, an assay with a B2GPI bound solid phase will not bind antibodies from other disease states, e.g., in syphilis positive samples, and will show better overall disease specificity.
A definite diagnosis of APS requires the presence of at least one clinical manifestation and one positive laboratory test result. The clinical criteria include thrombosis and one of the following three during pregnancy: one or more pregnancy losses after the 10th gestational week; one or more episodes of pre-term delivery before the 34th gestational week due to severe pre-eclampsia or severe placental insufficiency; or three or more recurrent pregnancy losses before the 10th gestational week. The laboratory criteria include the detection of IgG aCL or aB2GPI antibodies in moderate to high titers, in two different measurements at least 12 weeks apart; or detection of LA in two different measurements at least 12 weeks apart.
Anti-B2GPI antibodies have been reported to bind to epitopes located primarily on domains 1, 4, and 5 of the B2GPI molecule. Importantly, the main B2GPI epitope specifically associated with antiphospholipid syndrome has been reported to be a cryptic and conformation dependent structure that involves different regions of domain 1. If testing is positive for aB2GPI IgG antibodies, reflex testing will be performed to determine if the antibodies are directed to B2GPI domain 1. A positive B2GPI domain 1, IgG antibody test result may be useful in identifying patients at increased risk for arterial and venous thrombosis and pregnancy morbidity.
aPL antibodies are autoantibodies that react with negatively charged phospholipids (e.g. Cardiolipin). They are frequently found in sera of patients with systemic lupus erythematosus (SLE) and related diseases and are typical for the development of secondary APS. The presence of antiphospholipid antibodies in patients with no other autoimmune diseases is characteristic of primary APS. Because aCL antibodies are found in 80-90% of patients with APS, this test is very sensitive for the diagnosis of the syndrome. However, the aCL test is not specific to APS because aCL antibodies can also be detected in other autoimmune diseases, following administration of several drugs, and in the aftermath of infectious diseases (e.g., syphilis, hepatitis C and infectious mononucleosis).
B2GPI, also known as apolipoprotein H, is a 54 kDa serum cofactor (protein) that inhibits the intrinsic coagulation pathway and is involved in the regulation of blood coagulation. Detailed investigations about the nature of the cardiolipin-B2GPI complex have shown that B2GPI is the real autoantigen of anti-cardiolipin antibodies. In addition to being a prerequisite for binding to anti-cardiolipin antibodies, B2GPI has been identified as the primary antigen for these antibodies. Hence, an assay with a B2GPI bound solid phase will not bind antibodies from other disease states, e.g., in syphilis positive samples, and will show better overall disease specificity.
A definite diagnosis of APS requires the presence of at least one clinical manifestation and one positive laboratory test result. The clinical criteria include thrombosis and one of the following three during pregnancy: one or more pregnancy losses after the 10th gestational week; one or more episodes of pre-term delivery before the 34th gestational week due to severe pre-eclampsia or severe placental insufficiency; or three or more recurrent pregnancy losses before the 10th gestational week. The laboratory criteria include the detection of IgG aCL or aB2GPI antibodies in moderate to high titers, in two different measurements at least 12 weeks apart; or detection of LA in two different measurements at least 12 weeks apart.
Anti-B2GPI antibodies have been reported to bind to epitopes located primarily on domains 1, 4, and 5 of the B2GPI molecule. Importantly, the main B2GPI epitope specifically associated with antiphospholipid syndrome has been reported to be a cryptic and conformation dependent structure that involves different regions of domain 1. If testing is positive for aB2GPI IgG antibodies, reflex testing will be performed to determine if the antibodies are directed to B2GPI domain 1. A positive B2GPI domain 1, IgG antibody test result may be useful in identifying patients at increased risk for arterial and venous thrombosis and pregnancy morbidity.
