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Anti-phospholipid antibodies

Immunology

Sample and container requirements

Serum

Minimum volume required

1mL serum

Special requirements

None

Patient preparation

None

Sample viability

Turnaround time

7 days

Reference range

Anti-cardiolipin antibodies (99th centile): IgG anti-cardiolipin = >23.8 U/mL IgM anti-cardiolipin = >29.9 U/mL Anti-β-2-glycoprotein I antibodies (99th centile): IgG anti-β-2-glycoprotein I = >17.7 U/mL IgM anti-β-2-glycoprotein I = >5.7 U/mL

Clinical guidance

Consists of anti-cardiolipin (IgG / IgM) and β-2-glycoprotein I (IgG / IgM) antibodies. A complex group of autoantibodies associated with antiphospholipid syndrome where patients suffer from thrombosis (arterial and venous), particularly in recurrent unexplained thrombocytopenia, recurrent foetal loss, myocardial infarction and recurrent stroke. These antibodies may present in other connective tissue disease, particularly systemic lupus erythematosus (SLE). Antibody levels do not correlate with extent or severity of thrombosis. Anti-cardiolipin antibodies are also frequently detected in syphilis, HIV infected patients and other viral, bacterial and parasitic infections but are not correlated with the thrombosis risk or haematological manifestations of anti-phospholipid syndrome. Antibodies should therefore be repeated at least 12 weeks apart to provide evidence of a persistent autoantibody present. Lupus anticoagulant activity (performed by Haematology) should also be measured. Please refer to LabTestsOnlineUK for more information: https://labtestsonline.org.uk/tests/antiphospholipid-antibodies

Notes

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This information was last updated on 19 August 2026