The laboratory diagnosis of the antiphospholipid syndromes involves testing for both lupus anticoagulants and anticardiolipin antibodies in patients with clinical findings such as unexplained thrombosis or fetal wastage.
Testing
Interpretation
prolonged dRVVT, shortened by addition of cephalin
lupus anticoagulant
prolonged dRVVT, not shortened by addition of cephalin
coagulation factor defect
ELISA testing positive for IgG, IgA and IgM anticardiolipin antibodies with elevated titers, reported in PL (phospholipid) units
anticardiolipin antibodies, increased
ELISA testing positive for IgG, IgA and IgM anticardiolipin antibodies but levels within the normal range or minimally increased
anticardiolipin antibodies present, not significant
ELISA testing negative for IgG, IgA and IgM anticardiolipin antibodies
no anticardiolipin antibodies
where:
• dRVVT is the dilute Russell's viper venom test
• Testing for correction of dRVVT by addition of cephalin is termed cephalin neutralization.
Interpretation:
• If either lupus anticoagulants or increased anticardiolipin antibodies levels are present, then the antiphospholipid syndrome should be considered.
• The diagnosis of antiphospholipid antibody should not be made on a single abnormal test. It is important to demonstrate that the antibody is persistent in a patient with appropriate clinical findings, with at least 2 positive values at least 6 weeks apart.
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