What is the role of antithrombin III in the etiology of nonplatelet hemostatic disorders?

Updated: Oct 28, 2019
  • Author: Muhammad A Mir, MD, FACP; Chief Editor: Perumal Thiagarajan, MD  more...
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Answer

Answer

Antithrombin III, protein C, and protein S are all essential components of the coagulation process. All are synthesized by the liver and have a half-life in the range of 4-6 hours. Activated antithrombin III is a major inhibitor of thrombin and factor Xa, with smaller effects on factors IX, XI, and XII. Antithrombin III binds to the endothelial cell surface (proteoglycan heparan sulfate) in the presence of injury. It forms a subendothelial cell matrix that neutralizes thrombin by complexing with it. Antithrombin III serves as a cofactor for exogenous heparin, increasing its activity 1000- to 10,000-fold. [46]


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