Thrombotic Thrombocytopaenic Purpura (TTP)
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Aetiology
TTP is caused by ADAMTS13 deficiency
- More common: acquired (antibodies against ADAMTS13)
- Congenital ADAMTS13 deficiency is rare
ADAMTS13 is a plasma protein that cleaves VWF to regulate platelet adhesion and prevent excessive thrombosis.
Deficiency in ADAMTS13 → up-regulated VWF activity → promotes platelet aggregation and microvascular thrombosis.
Clinical Manifestation
Classic pentad:
- MAHA
- Thrombocytopaenia
- Renal impairment
- Fever
- Neurological symptoms (e.g. confusion, seizures)
The key features of TTP are MAHA + thrombocytopaenia, the classic pentad is rarely fully present.
Investigation and Diagnosis
| Investigation | Finding in TTP |
|---|---|
| FBC | Features of MAHA
Thrombocytopaenia |
| Blood film | Schistocytes (from MAHA) |
| Renal profile | Mild ↑ creatinine |
| Coagulation screen | Normal in TTP (helps exclude DIC) |
| ADAMTS13 activity | Severely reduced activity (<10%) – diagnostic of TTP |
Management
TTP is a haematological emergency and requires urgent treatment with:
- Plasma exchange (plasmapheresis) – cornerstone of acute management
- IV corticosteroids
- Adjuncts
- Rituximab
- Caplacizumab (anti-VWF nanobody)
Platelet transfusions are generally avoided in TTP, as they may worsen thrombosis.
It should only be used if there is life-threatening bleeding, under specialist direction.