Antiphospholipid syndrome - Connective tissue disorders

Antiphospholipid syndrome

Definition

A disorder characterised by the presence of autoantibodies directed against phospholipids or plasma proteins bound to phospholipids.

Aetiology/pathophysiology

Antiphospholipid syndrome may be primary/idiopathic or may occur secondary to SLE or other autoimmune disorders. The condition causes a thrombotic tendency due to loss of phospholipid dependent coagulation cofactors. Prothrombotic stimuli such as pregnancy, surgery, cigarette smoking, hypertension and the use of oral contraceptives further exacerbate this tendency. Antibodies include the lupus anti-coagulant (anti-coagulant in vitro but procoagulant in vivo), anti Î²2 glycoprotein-I antibodies and anticardiolipin antibodies.

Clinical features

Thrombosis: Venous thromboses are more common than arterial thromboses. These occur mainly in the deep veins of the calf. Other sites include renal, hepatic, subclavian and retinal veins. Arterial thrombosis in the cerebral vessels, coronary, renal and mesenteric arteries thromboses may also occur. Clinically patients may present with strokes, migraine, pulmonary embolism and infarction, thrombocytopenia, variable degrees of renal failure and amaurosis fugax.

Pregnancy: Some women suffer recurrent miscarriage especially during the late second and third trimester.

Non-thrombotic neurological manifestations include epilepsy, transverse myelitis, Guillain–Barre´ syndrome and chorea.

Cutaneous manifestations include livedo reticularis (a purplish mottled discolouration of the skin).

Investigations

Diagnosed by presence of anticardiolipin antibodies.

Management

Anticoagulation with aspirin for mild cases and warfarin in more severe cases reduces the risk of thrombosis. During the first and third trimester of pregnancy low-molecular-weight heparin is used due to the teratogenicity of warfarin and risks of bleeding in labour.