Thrombophilia due to inherited deficiency of blood antithrombin III (AT III, heparin cofactor, anticonvertin) in a Norwegian family was published 1965, Thromb. D. h. 13, 516 & 14, 473. Only a few families with this defect have since then been described in different countries. In another Norwegian family, two sisters, age 42 and 30, and a brother, 35, have had episodes of venous thrombosis and pulmonary embolism from the age of 24–29. Their father suffered from thrombosis and died at 67. The two sisters have blood AT III level about half of normal average, measured with a two-stage coagulation assay. Data from both families are compatible with an autosomal dominant inheritance of the plasma protein deficiency. Venous thrombosis in the families is remarkably often complicated with embolizations; this might also relate to an inadequate platelet function. Platelet aggregation time of PRP with added thrombin or ADP was found prolonged. In coumarin treatment of the patients, AT III assaying gave increased levels.
Successful treatment of a massive pulmonary embolism using rivaroxaban in a patient with antithrombin III deficiency
