Test Catalog

Test Id : GB2GP

Beta-2 Glycoprotein 1 Antibodies, IgG, Serum

Useful For
Suggests clinical disorders or settings where the test may be helpful

Evaluating patients with suspected antiphospholipid syndrome by identification of beta-2 glycoprotein 1 IgG antibodies

 

First-line test when antiphospholipid syndrome is strongly suspected, in conjunction with cardiolipin antibodies (IgG and IgM) and lupus anticoagulant testing

 

Estimating the risk of thrombosis and/or pregnancy-related morbidity in patients with systemic lupus erythematosus

Method Name
A short description of the method used to perform the test

Enzyme-Linked Immunosorbent Assay (ELISA)

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Beta 2 GP1 Ab IgG, S

Aliases
Lists additional common names for a test, as an aid in searching

B2GP1 (Beta-2 Glycoprotein 1)

Specimen Type
Describes the specimen type validated for testing

Serum

Additional Testing Requirements

Diagnostic criteria for antiphospholipid syndrome include the presence of at least one of the following: lupus anticoagulant, anticardiolipin, and anti-beta-2 glycoprotein 1 IgG or IgM antibodies. Consider ordering CLPMG / Phospholipid (Cardiolipin) Antibodies, IgG and IgM, Serum; MB2GP / Beta-2 Glycoprotein 1 Antibodies, IgM, Serum; and ALUPP / Lupus Anticoagulant Profile, Plasma concurrently with this test.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.4 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus OK
Heat-treated specimens Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 21 days
Frozen 21 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

Evaluating patients with suspected antiphospholipid syndrome by identification of beta-2 glycoprotein 1 IgG antibodies

 

First-line test when antiphospholipid syndrome is strongly suspected, in conjunction with cardiolipin antibodies (IgG and IgM) and lupus anticoagulant testing

 

Estimating the risk of thrombosis and/or pregnancy-related morbidity in patients with systemic lupus erythematosus

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Antiphospholipid syndrome (APS) has traditionally been described as a systemic autoimmune disease characterized by thrombosis or specific pregnancy-related morbidities associated with persistent documentation of "criterial" antiphospholipid antibody (aPL) tests.(1,2) Based on the 2006 revised Sapporo consensus classification, the "criterial" aPL antibody tests include lupus anticoagulant (LAC), and IgG/IgM antibodies to the cardiolipin (aCL) and beta-2-glyocoprotein I (anti-B2GPI) with all tests carrying equal diagnostic significance for disease.(1) In 2023, the American College of Rheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR) published new classification criteria for APS, which includes an entry criterion of at least one positive aPL antibody test within 3 years of identification of an aPL-associated clinical criterion, followed by additive weighted criteria (score range 1-7 points each) clustered into 6 clinical domains (macrovascular venous thromboembolism, macrovascular arterial thrombosis, microvascular, obstetric, cardiac valve, and hematologic) and 2 laboratory domains (LAC functional coagulation assays and solid-phase enzyme-linked immunosorbent assays [ELISA] for IgG/IgM aCL and/or IgG/IgM anti-B2GPI).(3) Of note, aPL antibodies also occur in patients with autoimmune diseases with significant prevalence in systemic lupus erythematosus (SLE) as well as other clinical manifestations (eg, heart valve disease, livedo reticularis, thrombocytopenia, nephropathy and neurological) often associated with APS.(1-3)

 

B2GPI is a 326-amino acid protein that is synthesized by hepatocytes, endothelial cells, and trophoblast cells.(4) It contains 5 repetitive structures or "sushi domains," termed domain 1 through 5, for a combined molecular weight of 54 kDa.(5-7) Autoantibodies to B2GPI may detected by solid-phase immunoassays (SPA) and functional coagulation assays. Unlike the LAC, the SPA provides quantitative measurements and antibody isotype class determinations that are important for risk assessment. Immunoassays for the detection and quantification of anti-B2GPI antibodies can be performed using either a composite substrate comprised of B2GPI plus anionic phospholipid (ie, cardiolipin-dependent B2GPI) or B2GPI alone. Antibodies detected using B2GPI substrate without another phospholipid (direct assays) are referred to simply as "anti-B2GPI 1 antibodies." Some anti-B2GPI antibodies are capable of inhibiting clot formation in functional coagulation assays that contain low concentrations of phospholipid cofactors.(5) Antibodies detected by functional coagulation assays are commonly referred to as LAC. Anti-B2GPI antibodies associated with thromboembolic events target domain 1 of the molecule and are responsible for LAC (functional, phospholipid-dependent prolongation of the clotting time) and aCL-dependent B2GPI antibody positivity.(2)

 

For the detection of anti-B2GPI IgG and IgM antibodies, the APS guidance advocates for the use of values above the 99th percentile of the laboratory's population in the establishment of reference intervals for tests. While this recommendation may be used for anti-B2GPI IgA immunoassays, there is no consensus for their determination.(6)

 

Thrombosis and obstetric complications are common clinical events in the general population and are not unique to APS; therefore, the presence of aPL antibodies is an absolute requirement for the diagnosis of definite APS.(1,5,7) Furthermore, aPL antibodies are heterogeneous with overlapping tendencies; the lack of aPL test harmonization or standardization requires the use of all 3 tests for optimal APS diagnosis.(1,3,6,7)

 

aPL antibodies were traditionally determined using the classic ELISA, with more diverse methods recently developed and adapted for clinical testing. Recognizing the analytical and diagnostic challenges associated with aPL antibody testing, initiatives to support assay harmonization and utilization, including the development of calibrators, test development, and validation efforts, as well as preanalytical, analytical, and postanalytical measures, have been published.(6-8) Overall, the interpretation and relevance of aPL antibody tests are dependent on factors such as the type of aPL (LAC, aCL or anti-B2GPI ), the source of cardiolipin and/or B2GPI , aPL antibody class (IgG, IgM or IgA) and level, as well as whether antibody positivity is single, double or triple.(1-3,6-8)

 

The 2023 ACR/EULAR classification criteria for APS are meant for clinical studies and may not be appropriate for routine patient evaluation and management. Therefore, in clinical practice, if suspicion for disease is high but criteria aPL antibody tests are inconclusive or negative, deviation from the APS diagnostic criteria may be justified. This may include testing for noncriteria aPL antibody tests, such the aCL IgA, anti-B2GPI IgA and anti-phosphatidylserine/prothrombin complex IgG and IgM antibodies.(2,6,9,10) However, there is no formal guidance for the measurement and interpretation of these non-criterial aPL antibodies in patients with APS or SLE.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

<15.0 SGU (negative)

15.0-39.9 SGU (weakly positive)

40.0-79.9 SGU (positive)

> or =80.0 SGU (strongly positive)

Results are reported in standard IgG anti-beta 2 glycoprotein 1 units (SGU).

 

Reference values apply to all ages.

Interpretation
Provides information to assist in interpretation of the test results

Positive results for beta-2 glycoprotein 1 (B2GPI) IgG antibodies, in association with specific clinical manifestations, may be diagnostic for antiphospholipid syndrome (APS). Low levels of B2GPIIgG antibodies, especially in the absence of other criteria phospholipid antibodies, should be interpreted with a high degree of suspicion.

 

Documentation of persistent anti- B2GPIIgG antibodies is a requirement for the diagnosis of definite APS. Antibodies must be detected on 2 or more occasions at least 12 weeks apart to fulfill the laboratory diagnostic criteria for APS.

 

Detection of B2GPIantibodies using the enzyme-linked immunosorbent assay method or other solid-phase immunoassays is not affected by anticoagulant treatment.

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Immunoassays for the detection of antiphospholipid (aPL) antibodies, including beta-2 glycoprotein 1 (B2GPI) may not completely distinguish between autoantibodies specific for antiphospholipid syndrome (APS) and those antibodies produced in response to infectious agents with or without thrombosis. Since these antibodies may be transiently produced, documentation of persistence as outlined in the 2006 revised Sapporo guidance for the criteria antibodies would constitute best practice, see Clinical Information.

 

Comparative studies and interlaboratory proficiency surveys indicate that results of phospholipid antibody tests can be highly variable, and results obtained with different commercial immunoassays may yield different results.(reviewed or documented in references 6-8)

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Miyakis S, Lockshin MD, Atsumi T, et al. International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS). J Thromb Haemost. 2006;4(2):295-306

2. Pengo V, Bison E, Denas G, Jose SP, Zoppellaro G, Banzato A. Laboratory diagnostics of antiphospholipid syndrome. Semin Thromb Hemost. 2018;44(5):439-444

3. Barbhaiya M, Zuily S, Naden R, et al. The 2023 ACR/EULAR antiphospholipid syndrome classification criteria. Arthritis Rheumatol. 2023;75(10):1687-1702

4. Lozier J, Takahashi N, Putnam F W: Complete amino acid sequence of human plasma beta 2 glycoprotein 1. Proc Natl Acad Sci U S A. 1984;81(12):3640-3644

5. Audrain MAP, El-Kouri D, Hamidou MA, el al. Value of autoantibodies to beta(2)-glycoprotein 1 in the diagnosis of antiphospholipid syndrome. Rheumatology (Oxford). 2002;41(5):550-553

6. Lakos G, Favaloro EJ, Harris EN, et al. International consensus guidelines on anticardiolipin and anti-beta 2-glycoprotein I testing: report from the 13th International Congress on Antiphospholipid Antibodies. Arthritis Rheum. 2012;64(1):1-10

7. Devreese KMJ. Solid phase assays for antiphospholipid antibodies. Semin Thromb Hemost. 2022;48(6):661-671

8. Tebo AE. Laboratory evaluation of antiphospholipid syndrome: An update on autoantibody testing. Clin Lab Med. 2019;39(4):553-565

9. Cousins L, Pericleous C, Khamashta M, et al. Antibodies to domain I of beta-2-glycoprotein I and IgA antiphospholipid antibodies in patients with ‘seronegative’ antiphospholipid syndrome. Ann Rheum Dis. 2015;74(01):317-319

10. Nakamura H, Oku K, Amengual O, et al. First-line, non-criterial antiphospholipid antibody testing for the diagnosis of antiphospholipid syndrome in clinical practice: A combination of anti-beta2 -glycoprotein I domain I and anti-phosphatidylserine/prothrombin complex antibodies tests. Arthritis Care Res (Hoboken). 2018;70(4):627-634

Method Description
Describes how the test is performed and provides a method-specific reference

Purified beta-2 glycoprotein 1 (B2GPI) antigen is bound to the wells of a polystyrene microwell plate under conditions that preserve the antigen in its native state. Prediluted controls and diluted patient sera are added to separate wells, allowing any B2GPI IgG antibodies present to bind to the immobilized antigen. Unbound sample is washed away, and an enzyme-labeled antihuman IgG conjugate is added to each well. A second incubation allows the enzyme-labeled antihuman IgG to bind to any patient antibodies that have attached to the microwells. After washing away any unbound enzyme-labeled antihuman IgG, the remaining enzyme activity is measured by adding a chromogenic substrate and measuring the intensity of the color that develops. The assay can be evaluated spectrophotometrically by measuring and comparing the color intensity that develops in the patient wells with that of a 5-point calibration curve. The standard used to construct this curve is referenced to the reference calibrators for IgG beta-2-Glycoprotein I available from the Rheumatology Lab, Seton Hall University, St. Joseph's Hospital and Medical Center. Semiquantitative results are reported in standard IgG anti-B2GPI units (SGU).(Package Insert: QUANTA Lite beta 2 GP1 IgG ELISA. Inova Diagnostics; Revision 19, 07/2020)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Saturday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

2 to 6 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

14 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
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Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

86146

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
GB2GP Beta 2 GP1 Ab IgG, S 44448-9
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
GB2GP Beta 2 GP1 Ab IgG, S 44448-9

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | PHP Pdf | CMS Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports