Thrombotic thrombocytopenic purpura





Aetiology

  • Post-infection e.g. urinary, gastrointestinal
  • Pregnancy
  • Drugs: ciclosporin, oral contraceptive pill, penicillin, clopidogrel, aciclovir
  • Tumours
  • SLE
  • HIV

Pathophysiology

Pathogenesis of thrombotic thrombocytopenic purpura (TTP)
  • Abnormally large and sticky multimers of von Willebrand's factor cause platelets to clump within vessels
  • In TTP there is a deficiency of ADAMTS13 (a metalloprotease enzyme) which breakdowns ('cleaves') large multimers of von Willebrand's factor
  • Overlaps with haemolytic uraemic syndrome (HUS)

Clinical features

  • Rare, typically adult females
  • Fever
  • Fluctuating neuro signs (microemboli)
  • Microangiopathic haemolytic anaemia
  • Thrombocytopenia
  • Renal failure

Management

  • No antibiotics - may worsen outcome
  • Plasma exchange is the treatment of choice
  • Steroids, immunosuppressants
  • Vincristine