Laboratory thrombophilias and venous thromboembolism.

Inherited abnormalities of coagulation are increasingly recognized in patients with venous thromboembolism. Common causes of hypercoagulability, also known as thrombophilia, include factor V Leiden, the prothrombin gene mutation, hyperhomocysteinemia, and antiphospholipid antibodies. Thrombophilia should be suspected in patients who develop idiopathic venous thromboembolism at a young age, recurrent thrombosis, thromboses at unusual sites, recurrent unexplained pregnancy loss, or if there is a family history of thrombotic disorders. The most cost-effective approach is to initially screen for factor V Leiden, the prothrombin gene mutation, hyperhomocysteinemia, and antiphospholipid antibodies because these are the most common defects causing thrombophilia. Long-term anticoagulation is controversial but should be considered if unprovoked venous thromboembolism recurs.