When should I consider referring a patient with suspected TTP to a specialist for further management?

When considering referring a patient with suspected thrombotic thrombocytopenic purpura (TTP), it is crucial to recognise that this is a serious condition requiring urgent specialist assessment and management, often initiated in emergency departments (Pascual-Izquierdo et al., 2023).

Referral to a specialist, typically haematology, should be considered urgently based on platelet count and associated clinical features, as TTP is characterised by severe thrombocytopenia ¹.

• Immediate referral or urgent specialist advice should be arranged for patients with a platelet count of less than 20 × 10⁹/L, or with active bleeding, due to the significantly increased risk of spontaneous haemorrhage below this threshold ¹.
• An urgent referral is indicated for patients with a platelet count of less than 50 × 10⁹/L ¹.
• For platelet counts within the range of 50–100 × 10⁹/L, an urgent referral should be arranged if associated with:
  • Evidence of pancytopenia (haemoglobin less than 100 g/L, neutrophils less than 1 × 10⁹/L) ¹.
  • Splenomegaly or lymphadenopathy ¹.
  • Pregnancy ¹.
  • Upcoming surgical or interventional procedures ¹.
• Patients with a platelet count of less than 100 × 10⁹/L that is persistent and unexplained (on at least two occasions 4–6 weeks apart) should be referred to haematology ¹.
• Additionally, any patient with a lowering platelet count trend, other haematological abnormalities, or who is generally unwell, should be referred ¹.

For adults with a low platelet count and abnormal bruising where non-accidental injury is not suspected, referral to a haematologist for further investigations is also appropriate, with the urgency determined by clinical judgement ². In pregnant women, close clinical observation is required as platelet counts may decrease before other clinical features of pre-eclampsia become apparent ¹.