Medicine & USMLE

Thrombotic Thrombocytopenic Purpura (TTP)

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Platelet Disorders
  1. Platelet Plug Formation
  2. Von Willebrand Disease
  3. Bernard-Soulier Syndrome
  4. Glanzmann Thrombasthenia
  5. Immune Thrombocytopenic Purpura (ITP)
  6. Thrombotic Thrombocytopenic Purpura (TTP)
  7. Hemolytic Uremic Syndrome (HUS)
  8. Disseminated Intravascular Coagulation (DIC)

Summary

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Key Points

  • hrombotic Thrombocytopenic Purpura (TTP)
    • Pathogenesis
      • Inhibition of ADAMTS13
        • Usually by autoantibody
        • ADAMTS is a metalloprotease enzyme that usually works to break down vWF
        • Impaired degradation of vWF → vWF multimers buildup → platelet aggregation → microthrombi formation → mechanical shearing of RBCs intravascularly
        • May require a secondary trigger (e.g. SLE, drugs)
    • Presentation
      • Typically affects young adult women
        • Due to autoimmune nature
      • Pentad of:
        • Thrombocytopenia
        • Microangiopathic hemolytic anemia (MAHA)
        • Acute kidney injury
          • Less common than in HUS
        • Fever
          • Not commonly seen with HUS
        • Neurologic symptoms (e.g. confusion)
          • Not seen in HUS
      • Mucocutaneous bleeding
        • Gingival bleeding, menorrhagia, petechiae, epistaxis
    • Diagnosis
      • Decreased platelet count
        • Due to consumptive microthrombi
      • Hemolytic anemia
        • Microthrombi adhesion can shear and damage RBCS
        • Schistocytes seen on peripheral smear
        • Elevated LDH
      • Increased bleeding time
        • Due to decreased platelet count
      • Normal PT/PTT
        • Helps distinguish vs. DIC
    • Treatment
      • Plasmapheresis (plasma exchange)
        • Life-saving therapy
      • Steroids
      • Rituximab