How do you test for antiphospholipid antibodies in a patient with Behçet's disease taking azathioprine and considering hormonal contraception?

Testing for Antiphospholipid Antibodies in Behçet's Disease

Test for antiphospholipid antibodies using a standard ELISA panel that includes anticardiolipin antibodies (IgG and IgM), anti-β2-glycoprotein I antibodies (IgG and IgM), and lupus anticoagulant, though these antibodies are not the primary driver of thrombosis in Behçet's disease and should not alter your immunosuppressive management approach. 1, 2

Specific Testing Protocol

Order the following three tests:

• Anticardiolipin antibodies (aCL) - both IgG and IgM isotypes by ELISA 1, 2

  • Values <10 GPL or MPL are considered negative 3
  • 10-40 GPL/MPL are low positive 3

  • 40 GPL/MPL are high positive 3

• Anti-β2-glycoprotein I antibodies (anti-β2-GPI) - both IgG and IgM isotypes by ELISA 1, 2

• Lupus anticoagulant (LA) - functional coagulation assay 4, 1

Interpretation in Behçet's Disease Context

Prevalence and significance:

• Approximately 20-25% of Behçet's patients will test positive for anticardiolipin antibodies, with low-level positivity predominating 4, 3

• Anti-β2-GPI antibodies are significantly elevated in Behçet's compared to controls (OR: 23.57) 1

• Critical distinction: Unlike in antiphospholipid syndrome or SLE, these antibodies in Behçet's disease appear to be "authentic" anticardiolipin antibodies that are NOT dependent on β2-glycoprotein I cofactor 2

• The thrombotic tendency in Behçet's is primarily driven by inflammatory vasculitis rather than hypercoagulability from antiphospholipid antibodies 4, 2

Clinical Implications for Your Patient

For vascular thrombosis management:

• The presence or absence of antiphospholipid antibodies should NOT change your treatment approach for deep vein thrombosis in Behçet's disease 5

• Continue with high-dose glucocorticoids plus immunosuppressives (azathioprine, cyclophosphamide, or cyclosporine-A) as the primary treatment for acute deep vein thrombosis 5

• Anticoagulation may be added cautiously, but only after ruling out pulmonary artery aneurysms and ensuring low bleeding risk 5

For hormonal contraception considerations:

• Oral contraceptives carry at least a 2-fold increased risk for Budd-Chiari syndrome in thrombotic conditions 5

• Given that your patient already has Behçet's disease with its inherent thrombotic risk, avoid estrogen-containing contraceptives regardless of antiphospholipid antibody status 5

• Consider progesterone-only methods or non-hormonal alternatives

Important Caveats

Do not over-interpret positive results:

• There is no distinct correlation between antiphospholipid antibody positivity and vascular complications in Behçet's disease 4

• The thrombotic diathesis in Behçet's is a "much more complicated and multifactor process" than antibody-mediated thrombosis 4

• One study found that visual acuity was significantly worse in Behçet's patients with elevated anticardiolipin antibodies, suggesting possible prognostic value for ocular disease 3

Testing rationale:

• Test primarily to rule out coexistent antiphospholipid syndrome (a separate entity) rather than to guide Behçet's-specific management 1, 2

• The immunosuppressive regimen (azathioprine) your patient is already receiving for Behçet's disease is the appropriate treatment regardless of antibody status 5