Idiopathic Thrombocytopenic Purpura



  • Idiopathic thrombocytopenic purpura (ITP) is thrombocytopenia without apparent cause or abnormalities in other cell lines
  • Incidence is ∼2–5/100,000/yr – may be an underestimate owing to undetected, subclinical cases
  • Acute ITP:
    • 1/2 of cases involve children
    • 80% of children recover within 8 wk with or without therapy
    • Adult recovery is delayed and requires specific therapy to achieve remission
  • Chronic ITP:
    • Platelets <150,000 for >6 mo following a diagnosis of ITP
    • Occurs mostly in adults
    • Young women are most susceptible in adult-onset ITP
    • Characterized by variable response to corticosteroids and other immune suppressants
    • 60–70% respond to splenectomy
  • Chronic refractory ITP:
    • Platelet counts may often wax and wane
    • Often do not respond to therapy
    • No clear optimal course of treatment
  • Genetics:
    • ITP appears to run in families, as do variations in response to corticosteroids for treatment


  • Autoantibodies produced by B-cells and plasma cells cause immune-mediated destruction of circulating platelets
  • Macrophages in spleen and liver mediate destruction of platelets via IgG autoantibodies
  • IgM and IgA rarely have been seen
  • Some patients do not possess autoantibodies, suggesting a role for T-cell–mediated cytotoxicity
  • C3 and C4 complements have also been shown to play a role in patients that lack autoantibodies
  • Poor platelet production may also play a role especially in chronic or refractory cases of ITP
  • Eradication of Helicobacter pylori can sometimes be associated with platelet recovery (unclear mechanism)

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