Recurrent venous thrombosis and hypercoagulable states.

Patients with recurrent venous thrombosis, or those with thrombosis at a young age (less than 45 years) and a family history of thrombotic disorders, may have an inherited hypercoagulable disorder. The most common disorders are deficiencies of protein S, protein C and antithrombin III, inhibitors of the coagulation cascade. These deficiencies may be found in approximately 10 percent of patients who are under age 45 and have venous thrombosis. Acquired disorders associated with recurrent venous thrombosis include carcinoma and antiphospholipid antibody syndrome. Appropriate anticoagulation can reduce the risk of recurrent thrombosis in patients with inherited and acquired abnormalities.