Definitive diagnosis of antiphospholipid syndrome

A definitive diagnosis of antiphospholipid syndrome requires:

• presence of at least one of the clinical criteria and
• positive results for at least one of the three assays on at least two separate occasions 12 weeks apart

The following tests can be used in patients who have indications for testing for antiphospholipid antibodies:

• testing for LA
  • is the most predictive test for thrombosis
  • the presence of IgG anticardiolipin antibodies (aCL) or IgG anti beta2-glycoprotein I (beta2GPI) in those who are LA positive increases the specicity
• testing for IgG antibodies to beta2GPI
  • can be detected either by an IgG aCL ELISA or an IgG anti-beta2GPI ELISA
  • an aCL ELISA may detect anti bodies to other phospholipid binding proteins as well as anti-beta2GPI.

The first test results should be obtained before starting anticoagulants (due to its effect on LA test) (2).

Patients with a positive test results should be referred to a specialist (2)

Reference:

• (1) Keeling D et al.Guidelines on the investigation and management of antiphospholipid syndrome. Br J Haematol. 2012;157(1):47-58.
• (2) Cohen D et al. Diagnosis and management of the antiphospholipid syndrome. BMJ. 2010;340:c2541