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
- Insufficient ADAMTS-13 activity allows vWF multimers to accumulate in microcirculation
- Similar to but different from HUS (which is more common in peds)
- Microangiopathic hemolytic anemia + low plts is TTP until proven otherwise
- Can occur as a result of Plavix (clopidogrel) use (usually within first 2 wk of starting)
Risk Factors
- Congenitally deficient ADAMTS-13 activity and:
- Pregnancy
- Infection
- Inflammation
- Medication use (quinolones, ticlopidine, clopidogrel)
Clinical Features
- Pentad
- Microangiopathic hemolytic anemia (MAHA)
- Thrombocytopenia
- Fever
- Renal pathology
- CNS abnormalities (seizure, AMS, CVA, coma)
- TTP pentad mnemonic = FAT RN
- Fever, Anemia, Thrombocytopenia, Renal, Neuro sx
DDX
- Other microangiopathic hemolytic anemias (eg, HUS, DIC, malignant hypertension)
- 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
See Also
Source
- Tintinalli
- Harwood Nuss