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