Thrombotic thrombocytopenic purpura

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

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

Clinical Features

1. Pentad
   1. CNS abnormalities
      1. Seizure, CVA, coma
   2. Renal pathology
   3. Microangiopathic hemolytic anemia
   4. Thrombocytopenia
   5. Fever

DDX

1. Sepsis
2. SLE
3. HELLP syndrome
   1. Difficult to distinguish
   2. Anemia, plt count, and LDH tend to be more severe in TTP; LFTs more severe in HELLP

Work-Up

1. CBC
   1. Anemia, schistocytes, thrombocytopenia
2. LDH
3. Haptoglobin
4. UA
   1. Hemoglobinuria
   2. Creatinine
5. LFT
   1. Increased bilirubin
6. PT/PTT/INR
   1. Normal (differentiates from DIC)
7. Urine pregnancy
   1. Significant association between pregnancy and TTP

Treatment

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

Disposition

• Admit for plasma exchange

Source

• Tintinalli
• Harwood Nuss