Thrombotic Thrombocytopenic Purpura (TTP)

  • TTP = Thrombotic Microangiopathy (TMA)
  • Core features:
    • MAHA
    • Thrombocytopenia

Types of TMA

  • TTP
    • ADAMTS13 deficiency
      • Cleaves vWF multimers
      • Deficiency → large vWF multimers → platelet trapping
    • Acquired
      • 95%
      • Autoantibody
    • Hereditary
      • 5%
  • HUS
    • Typical
      • childhood
      • Shiga / Shiga-like toxin
    • Atypical
      • Adult
      • Complement-mediated
  • Drug-induced TMA

Pathophysiology

  • Microthrombi in arterioles & capillaries
  • Platelet consumption → thrombocytopenia
  • RBC fragmentation → MAHA

Clinical Features

  • Bleeding
  • Anemia symptoms
  • Neurological:
    • Headache
    • Confusion
    • Young stroke
  • Renal involvement
    • Absent

Laboratory Findings

  • Platelets ↓
  • Hemoglobin ↓
  • Haptoglobin ↓
  • LDH ↑
  • Coombs – Negative
  • Peripheral smear
    • Schistocytes
  • RFT / LFT
    • Normal

HUS vs TTP

Feature
HUS
TTP
Major organ
Kidney
Brain
Renal failure
Present
Absent

Management

  • Plasma exchange (PLEX) + Rituximab – TOC

TTP Mimics

  • Malignant hypertension
  • Antiphospholipid antibody syndrome
  • Sepsis
  • Pre-eclampsia
  • Scleroderma renal crisis

Drug-induced TMA

  • Mitomycin
  • Cisplatin
  • Gemcitabine
  • Calcineurin inhibitors
  • Ticlopidine
  • Clopidogrel