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Antiphospholipid Syndrome (APS) Testing Opportunities
According to international classification criteria, identification of APS requires the presence of vascular thrombosis and/or pregnancy morbidity, along with at least 1 of the following antiphospholipid antibody tests: Lupus Anticoagulant (LA), Anticardiolipin (aCL) IgG and/or IgM antibodies, and Anti-β2-glycoprotein I (β2-GPI) IgG and/or IgM antibodies.1
CLASSIFICATION CRITERIA FOR THE DEFINITIVE DIAGNOSIS OF APS1
| ≥1 CLINICAL CRITERIA |
≥1 LABORATORY CRITERIA Positive results must be confirmed on ≥2 occasions, at least 12 weeks apart. |
| Vascular thrombosis: ≥1 arterial, venous, or small vessel thrombosis |
Anticardiolipin (aCL) antibodies (IgG and/or IgM) in serum or plasma present in medium or high titer (i.e. >40 GPL or MPL, or >the 99th percentile). |
| Pregnancy morbidity ≥1 unexplained deaths of a morphologically normal fetus at or beyond gestational week 10; ≥1 premature births at or before gestational week 34; ≥3 unexplained miscarriages before gestational week 10 |
Anti β2-glycoprotein I (β2GPI) antibodies (IgG and/or IgM) in serum or plasma in titer >the 99th percentile. |
| Lupus anticoagulant (LAC) present in plasma |
Detailed clinical and laboratory assessments are very important to provide a full picture of APS. Using lupus anticoagulant, IgG anti-cardiolipin, and IgG anti-β2-glycoprotein I can help:2
Confirm a diagnosis of APS
Identify patients at higher risk of recurrence or developing clinical events
Provide patients with appropriate treatment (depending on their risk profile) earlier in their journey, potentially improving their quality of life
WHO SHOULD BE TESTED
Patients who should be screened for antiphospholipid antibodies include:4
- Patients with unprovoked proximal deep vein thrombosis or pulmonary embolism after stopping anticoagulation for at least seven days
- Young adults, (i.e. aged under 50), with ischemic stroke
- Women with recurrent pregnancy loss, defined as more than 3 pregnancy losses before 10 weeks’ gestation
Patients should be tested for lupus anticoagulant, anti-cardiolipin (aCL) antibodies, and anti-β2-glycoprotein I antibodies.1 Due to the low sensitivity and specificity of these tests, they should always be interpreted in the context of each other and the clinical history. Lupus anticoagulant is the most predictive test for thrombosis. The presence of anti-cardiolipin or anti-β2-glycoprotein I, in those who are lupus anticoagulant positive, increases specificity. As a single positive test can result from a short-term infection, tests should be repeated after an interval of 12 weeks to demonstrate persistence.4,5
Tests Available to Help Confirm APS
All EliA™ assays for APS are proven to have diagnostic relevance. Their specificity and sensitivity have been evaluated in a study that included three other commercially available diagnostic assays. Two panels from groups of 50 and 51 APS patients, respectively, were evaluated along with results from 301 patients with other diseases. The EliA assays for APS were shown to have excellent specificity and sensitivity, proving its diagnostic performance. Specific results for Cardiolipin IgG and IgM, and β2-glycoprotein I IgG and IgM, are shown below.
EliA™ Cardiolipin IgG6
Reference Values
Measuring range: 0.5–418 GPL-U/mL
| Value | Classification |
| <10 GPL-U/ml | Negative |
| 10-40 GPL-U/ml | Weak Positive |
| >40 GPL-U/ml | Positive |
Sample material: Serum, plasma (EDTA, citrate, heparin)
EliA Cardiolipin IgA7
Reference Values
Measuring range: 0.3 - 181 APL-U/ml
| Value |
Classification |
| < 14 APL-U/ml | Negative |
| 14 – 20 APL-U/ml | Equivocal |
| > 20 APL-U/ml | Positive |
Sample material: Serum, plasma (EDTA, citrate, heparin)
EliA Cardiolipin IgM8
Reference Values
Measuring range: 0.8–472 MPL-U/ml
| Value |
Classification |
<10 EliA MPL-U/ml |
Negative |
| 10–40 EliA MPL-U/ml | Weak Positive |
| >40 EliA MPL-U/ml | Positive |
Sample material: Serum, plasma (EDTA, citrate, heparin)
EliA β2-glycoprotein I IgA9
Reference Values
Measuring range: 0.3 - 183 U/ml
| Value |
Classification |
| < 7 U/ml | Negative |
| 7 - 10 U/ml | Equivocal |
| > 10 U/ml | Positive |
Sample material: Serum, plasma (EDTA, citrate, heparin)
EliA β2-glycoprotein I IgG10
Reference Values
Measuring range: 0.6–532 U/mL
| Value | Classification |
| <7 U/ml | Negative |
| 7–10 U/ml | Equivocal |
| >10 U/ml | Positive |
Sample material: Serum, plasma (EDTA, citrate, heparin)
EliA β2-glycoprotein I IgM11
Reference Values
Measuring range: 2.9–576 EliA U/mL
| Value |
Classification |
| <7 U/ml | Negative |
| 7–10 U/ml | Equivocal |
| >10 U/ml | Positive |
Sample material: Serum, plasma (EDTA, citrate, heparin)
Reference values apply to all ages. Reference values and sample materials have been taken from respective Phadia 250 instrument Directions for Use. These data are intended as a guide and should be treated accordingly. Good laboratory practice requires that each laboratory establishes its own range of expected values.
If you have any questions or uncertainty please contact us.
- 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.
- Meroni LP, Chighizola CB, Rovelli F, et al. Antiphospholipid syndrome in 2014: more clinical manifestations, novel pathogenic players and emerging biomarkers. Arthritis Res Ther. 2014; 16:209.
- Devreese KMJ, Pierangeli SS, De Laat B, et al. Testing for Antiphospholipid Antibodies with Solid Phase Assays: guidance from the SSC of the ISTH. J Thromb Haemost. 2014;12:792-5.
- Keeling D, Mackle I, Moore GW, et al. Guidelines on the investigation and management of antiphospholipid syndrome. Br J Haematol. 2012;157:47-58.
- Pengo V, Ruffatti A, Del Ross T, et al. Confirmation of initial antiphospholipid antibody positivity depends on the antiphospholipid antibody profile. J Throm Haemost. 2013 Aug;11(8):1527-31.
- Phadia™ EliA Cardiolipin IgG Directions for Use for the Phadia 250 Laboratory System. Issued April 2017.
- EliA Cardiolipin IgA Directions for Use for the Phadia 250 Laboratory System. Issued April 2017.
- EliA Cardiolipin IgM Directions for Use for the Phadia 250 Laboratory System. Issued April 2017.
- EliA Beta 2 Glycoprotein I IgA Directions for Use for the Phadia 250 Laboratory System. Issued March 2017.
- EliA Beta 2 Glycoprotein I IgG Directions for Use for the Phadia 250 Laboratory System. Issued March 2017.
- EliA™ Beta 2 Glycoprotein I IgM Directions for Use for the Phadia 250 Laboratory System. Issued April 2017.
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