Antithrombin Activity, Plasma Diagnosis of antithrombin
deficiency, acquired or congenital Monitoring treatment of
antithrombin deficiency disorders, including infusion of
antithrombin therapeutic concentrate Clinical Information
Discusses physiology, pathophysiology, and general clinical
aspects, as they relate to a laboratory test Antithrombin is a
member of the serine protease inhibitor (serpin) superfamily. It
is the principal plasma anticoagulant serpin mediating
inactivation of serine protease procoagulant enzymes, chiefly
thrombin and coagulation factors Xa and IXa.(1) Heparin and
certain other naturally occurring glycosaminoglycans markedly
enhance antithrombin's anticoagulant activity (approximately
1,000-fold) by providing a template to catalyze formation of
covalently bonded, inactive complexes of serine protease and
antithrombin that are subsequently cleared from circulation.
Antithrombin is the mediator of heparin's anticoagulant
activity. The antithrombin gene on chromosome 1 encodes a
glycoprot