[Venous thromboembolic disease: which coagulation screening, for whom, when?].

Testing for laboratory evidence of thrombophilia is now common but it has limited predictive value for the majority of unselected symptomatic patients. So when is testing indicated ? And which one? The term "thrombophilia" describes disorders of the haemostatic mechanisms which are likely to predispose to thrombosis. Thrombophilia may be heritable, acquired or mixed, resulting of the environment interacting with genetic background. To date, a limited number of genetic variants and other defects are proven to be independent risk factors for venous thromboembolism. These include antithrombin deficiency, protein C deficiency, protein S deficiency, factor V Leiden, the prothrombin gene mutation, hyperhomocysteinemia and antiphospholipid antibodies. There is no good evidence currently available to support the hypothesis that heritable thrombophilias increase the risk of arterial disease. But acquired or mixed thrombophilias such as hyperhomocysteinemia and antiphospholipid antibodies have been found in association with both venous and arterial thrombotic disorders. When testing for thrombophilia is indicated, especially in case of venous thromboembolism, it should include assays for heritable, mixed or acquired defects: deficiency of antithrombin, protein C or protein S, factor V Leiden and prothrombin G20210A mutations, elevated factor VIII, hyperhomocysteinemia and for antiphospholipid antibodies. Depending on the site of venous thrombosis, laboratory testing to exclude myeloproliferative disorders should be performed.