Chapter 84: The Antiphospholipid Syndrome

INTRODUCTION

The antiphospholipid syndrome is an acquired thrombotic disorder associated with circulating autoantibodies to anionic phospholipid–protein complexes.
These antibodies were first detected as inhibitors of the partial thromboplastin time in patients with systemic lupus erythematosus (SLE) and, for this reason, were called “lupus anticoagulant,” although this finding is not limited to patients with lupus.

The disorder is generally considered to be autoimmune, although a direct causal relationship between antiphospholipid antibodies and thrombosis or pregnancy problems has not been demonstrated.
The antiphospholipid antibodies found in the syndrome usually react with phospholipid bound to a plasma protein.
A number of pathogenetic mechanisms have been proposed for the antiphospholipid syndrome, and it is possible that several of these act in concert to cause the disorder.

Patients usually present with manifestations of thrombosis and/or pregnancy complications or loss.
The disease usually presents in patients between ages 35 and 45 years. Both sexes are equally susceptible.
The disorder is considered “secondary antiphospholipid syndrome” if the patient has a recognizable autoimmune disease, or “primary antiphospholipid syndrome” if there is no associated disorder.
Table 84–1 summarizes the clinical manifestations of the antiphospholipid syndrome.
The antiphospholipid syndrome should be considered in patients with recurrent thromboses in unusual locations.
Venous and/or arterial thromboses may occur at any site but are most frequent in the lower extremities.
Patients with concurrent inherited thrombophilia who develop antiphospholipid antibodies are at increased risk for thrombosis.
Immune thrombocytopenia, usually of mild to moderate severity, occurs frequently in patients with antiphospholipid syndrome.
Rarely, patients may develop a catastrophic form of the antiphospholipid syndrome, with severe, widespread vascular occlusions, despite intense anticoagulant treatment, often leading to death.
Recurrent pregnancy loss occurs often in women with the antiphospholipid syndrome. About one-half of the abortions occur after the first trimester.
Some patients develop a bleeding disorder because of a concurrent coagulopathy, such as acquired hypoprothrombinemia, or because of acquired inhibitors of factor VIII (see Chap. 82).

TABLE 84–1CLINICAL MANIFESTATIONS OF THE ANTIPHOSPHOLIPID SYNDROME

TABLE 84–1 CLINICAL MANIFESTATIONS OF THE ANTIPHOSPHOLIPID SYNDROME

Venous and arterial thromboembolism*
Pregnancy complications attributable to placental insufficiency, including spontaneous pregnancy losses, intrauterine growth restriction, preeclampsia, preterm labor, and placental abruption*
Thrombocytopenia
Thrombotic and embolic stroke*
Cerebral vein thrombosis*
Livedo reticularis, necrotizing skin vasculitis
Coronary artery disease
Valvular heart disease
Kidney disease
Pulmonary hypertension
Acute respiratory distress syndrome
Atherosclerosis and peripheral artery disease
Nonthrombotic retinal disease
Adrenal failure, hemorrhagic adrenal infarction*
Budd-Chiari syndrome, mesenteric and portal vein obstructions, hepatic infarction, esophageal necrosis, gastric and colonic ulceration, gallbladder necrosis^*
Catastrophic antiphospholipid syndrome with thrombotic microangiopathy*

*Manifestations that qualify as consensus criteria for diagnosis of antiphospholipid syndrome.

Source: Williams Hematology, 9th ed, Chap.131, Table 131–4.

Diagnosis of the antiphospholipid syndrome requires demonstration of antibodies against ...

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