Changes of antithrombin III (AT III) in AT III deficient patients during long-term anticoagulant treatment

Antithrombin III deficient patients with manifest thromboembolic diseases need long term coumarin treatment. There are contradictory data on the change of AT III during this therapy. The authors observed 5 patients with severe AT III decrease type I, 3 with functional abnormality and 2 with a pathological heparin binding. AT III function was determined by the Gerendás-Rák method and with chromogenic substrate. AT III antigen was measured with Behring M-Partigen and Laurell rocket electrophoresis. Crossed immunoelectrophoresis was carried out in all patients. In patients with type I AT III decrease, AT III hasn't changed even in a long period of more than 10 years. In the other types AT III became normal. The pathological heparin binding wasn't changed.