Coags

Antithrombin III Deficiency

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Antithrombin III Deficiency, Antithrombin 3 Deficiency, AT3 Deficiency, AT3D

  • See Also
  1. Thrombophilia
  2. Deep Vein Thrombosis
  3. Pulmonary Embolism
  4. Anticoagulation in Thromboembolism
  • Epidemiology
  1. Rare cause of Thrombophilia
  2. First episode of thrombosis occurs ages 10-30 years
  • Pathophysiology
  1. Antithrombin III (AT3) is a Glycoprotein produced by the liver
    1. Antithrombin III Deficiency (AT3 Deficiency) is an inherited Autosomal Dominant trait (or may be acquired)
    2. Heterozygous AT3 Deficiency patients have 25-50% AT3 functional levels
  2. Antithrombin III (AT3) normally inhibits clotting, Coagulation Factors (enhanced by Heparin)
    1. Factor IXa
    2. Factor Xa
    3. Factor XIa
    4. Factor XIIa
    5. Thrombin
  3. Antithrombin III Deficiency results in Thrombophilia
    1. Deep Vein Thrombosis
    2. Pulmonary Embolism
  • Causes
  1. Inherited Antithrombin III Deficiency (most common)
  2. Acquired Causes
    1. Liver Failure
    2. Malnutrition
    3. Nephrotic Syndrome (AnticoagulationProtein loss including AT3)
  • Labs
  1. Functional level Antithrombin III
  • Management
  1. See Thrombophilia
  2. See Venous Thromboembolism
  3. See Anticoagulation in Thromboembolism
  • Complications
  1. Recurrent Miscarriage
  2. Venous Thromboembolism (DVT, PE)
    1. Up to 50% lifetime Prevalence (esp. in teen years during hormonal increases)
  • References
  1. Jean-Louis and Sethuraman (2023) Crit Dec Emerg Med 37(7): 4-11