Management of patients with hereditary hypercoagulable disorders

The inherited hypercoagulable states can be divided into those that are com mon and associated with a modest risk of thrombosis (i.e, factor V Leiden a nd G20210A prothrombin gene) and those that are uncommon but asssociated wi th a high risk of thrombosis. There is no convincing evidence that, indepen dent of other clinical factors, the presence of factor V Leiden or the prot hrombin gene mutation should influence the use of primary prophylaxis or th e duration of anticoagulant therapy following an episode of thrombosis. Ind rect evidence sugests that the presence of antithrombin, protein C deficien cy, or protein S deficiency justifies avoiding additional risk factors for thrombosis, such as estrogen therapy, and justifies use of more aggressive primary prophylaxis when additional risk factors cannot readily be avoided (e.g. pregnancy). The presence of one of these three abnormalities also fav ors more prolonged anticoagulant therapy following venous thrombosis. Howev er, their presence or absence appears to have less influence on the risk of recurrent venous thromboembolism than whether thrombosis was provoked by a major reversible risk factor, such as surgery.