Teaching Points:

• TTP is a hematologic emergency. It is manifested by the clinical pentad of:
  • Thrombocytopenia
  • Microangiopathic hemolytic anemia (schistocytes on smear)
  • Acute renal insufficiency
  • Fevers
  • Encephalopathy
• Only need thrombocytopenia and MAHA in order to make the diagnosis
• Treatment involves initiation of plasmapheresis
• ADAMTS 13 Testing
  • ADAMTS 13 functions as a protease that cleaves the von Willebrand multimers
  • Deficiency of ADAMTS 13 leads to accumulating amounts of vWF, causing platelet aggregation (leading to thrombocytopenia) and disruption/breaking of RBCs (MAHA)
  • Activity influenced by plasma products and transfusions.
  • Levels of Activity
    • >50% activity argues against TTP.
    • <10% activity suggests TTP
    • 10-50% activity is an ambiguous area
  • Presence of an ADAMTS13 inhibitor
    • Presence suggested acquired TTP
    • Lack of inhibitor suggests hereditary cause of TTP.