Medicine & USMLE

Antithrombin-3 Deficiency

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Coagulation
  1. Common Pathway of Coagulation
  2. Extrinsic Pathway of Coagulation
  3. Intrinsic Pathway of Coagulation
  4. Hemophilia A
  5. Hemophilia B
  6. Hemophilia C
  7. Factor V Leiden
  8. Antithrombin-3 Deficiency

Summary

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Key Points

  • Antithrombin-3 Deficiency
    • Pathogenesis
      • Inherited deficiency of antithrombin-3
        • Antithrombin 3 usually works to inhibit factors IIa and Xa
        • Decreased inhibition of factors IIa and Xa → hypercoagulability
      • May be acquired
        • Renal failure or nephrotic syndrome
          • Loss of antithrombin-3 in the urine
        • Liver failure
          • Inability to produce antithrombin-3 in the liver
    • Genetics
      • Autosomal dominant inheritance
    • Presentation
      • Recurrent thrombosis (clots)
        • Especially at a young age in otherwise healthy individual
        • Venous > arterial
        • DVT
        • PE
    • Diagnosis
      • Normal PT, PTT, thrombin time
        • No direct effect on secondary hemostasis as measured in the laboratory setting
      • Diminished increase in PTT after heparin administration
    • Treatment
      • Anticoagulants as needed for thrombosis
      • Antithrombin replacement therapy