Thrombotic thrombocytopenic purpura

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Background

  • Pathophysiology
    • Insufficient ADAMTS-13 activity allows vWF multimers to accumulate in microcirculation
      • Leads to platelet aggregation/thrombocytopenia and hemolysis of RBCs
  • Similar to but different from HUS (which is more common in peds)
  • Microangiopathic hemolytic anemia + low plts is TTP until proven otherwise

Risk Factors

  • Congenitally deficient ADAMTS-13 activity and:
  1. Pregnancy
  2. Infection
  3. Inflammation
  4. Medication use (quinolones, ticlopidine, clopidogrel)

Clinical Features

  • Pentad
  1. Microangiopathic hemolytic anemia
  2. Thrombocytopenia
  3. Fever
  4. Renal pathology
  5. CNS abnormalities (seizure, AMS, CVA, coma)
  • TTP pentad mnemonic = FAT RN
    • Fever, Anemia, Thrombocytopenia, Renal, Neuro sx

DDX

  • Other microangiopathic hemolytic anemias (HUS, DIC, malignant HTN)
  • ITP
  • Sepsis
  • SLE
  • HELLP syndrome
    • Difficult to distinguish
    • Anemia, plt count, and LDH tend to be more severe in TTP; LFTs more severe in HELLP

Work-Up

  • CBC with peripheral smear (anemia, schistocytes, thrombocytopenia)
  • LDH (elevated)
  • Haptoglobin (decreased)
  • Reticulocyte count (appropriate)
  • UA (hemoglobinuria)
  • Creatinine (possibly elevated)
  • LFTs (increased bilirubin)
  • PT/PTT/INR (normal; differentiates from DIC)
  • Urine pregnancy (significant association between pregnancy and TTP)

Treatment

  • Plasma exchange (plasmapheresis)
    • Replaces defective or insufficient ADAMTS-13 and clears vWF multimers
  • Transfusion
    • Indicated if plasma exchange cannot be performed immediately
    • FFP
    • Platelet (only for life-threatening bleeding or intracranial hemorrhage)
      • Platelet infusion may lead to acutely worsened thrombosis, renal failure, and death
  • Splenectomy - 2nd line therapy

Disposition

  • Admit for plasma exchange

Source

  • Tintinalli
  • Harwood Nuss