Immune Thrombocytopenic Purpura

Classification

Can be classified by aetiology:

• Primary ⇒ autoimmune disorder characterised by isolated thrombocytopenia (most common)
• Secondary ⇒ secondary to identifiable trigger:
  • Autoimmune disorders → antiphospholipid syndrome
  • Malignancy → Lymphoma, Leukaemia (particularly CLL)
  • Infection → HIV, HCV
  • Drugs → many check AMH
• Can be classified by chronicity:
  • Newly diagnosed ITP ⇒ all cases <3 months of diagnosis
  • Persistent ITP ⇒ ITP lasting 3-12 months
  • Chronic ITP ⇒ ITP lasting >12 months

Epidemiology

• US Statistics:
  • Females affected more than males
  • Children :: highest prevalence <5 years old; typically self-limiting after viral infection; 80% resolve in 12 months
  • Adults :: highest prevalence in >55 years old; often incidental finding on routine CBC

Pathophysiology

• Antiplatelet antibodies (mostly IgG directed against GpIIb/IIIa, GpIb/IX, bind to surface proteins on platelets → sequestration by spleen and liver → ↓ platelet count → ↑ bone marrow megakaryocytes and platelet production)

Clinical Features

• Splenomegaly is typically absent in patients with ITP
• Clinical features can correlate with platelet count; but most patients are asymptomatic:
• Minor mucocutaneous bleeding is possible:
  • Subcutaneous bleeding (e.g. bruising, petechiae, purpura)
  • Mucosal bleeding (e.g. mild epistaxis, gingival bleeding)

Investigations

• CBC: typically $100,000\frac{\mathrm{count}}{\mathrm{m}{\mathrm{m}}^3}$
• Coagulation panel is usually normal (unless secondary ITP)
• Bleeding time may be ↑

Diagnosis

• ITP is often a diagnosis of exclusion in patients who have thrombocytopenia with no other abnormalities

Management

• In all patients stop medications that impair platelet function (e.g. NSAIDs)

Emergency Treatment

• Indicated for patients with:
  • Life threatening bleeding (typically at platelet $<20,000\frac{\mathrm{count}}{\mathrm{m}{\mathrm{m}}^3}$)
  • Acute neurological features (i.e. intracranial bleed)
  • Anticipated urgent surgery or invasive procedure

Emergency Management:

1. Haemostatic control of bleeding (if present)
2. Start combination therapy with:
   • Corticosteroids (e.g. methylprednisolone)
   • • IV immunoglobulin
   • • Platelet transfusions as needed
3. If ⌀ response consider thrombopoietin receptor agonist (TPO-RA) e.g. romiplostim

Conservative Managmenet

• Indicated for asymptomatic or minor mucutaneous bleeding only patients with:
  • Adults with a platelet count $>30,000\frac{\mathrm{count}}{\mathrm{m}{\mathrm{m}}^3}$
  • Children with any platelet count
• Remember to refer to haematology and counsel on bleeding risks¹

First Line Medical Therapy

• Indicated for:
  • Adults with platelet count $<30,000\frac{\mathrm{count}}{\mathrm{m}{\mathrm{m}}^3}$
  • Patients with significant non-life-threatening mucosal bleeding (e.g. severe epistaxis)
  • Symptoms impacting quality of life
• Therapy:
  • Corticosteroids (e.g. dexamethasone or prednisone)
  • If contraindicated or not tolerated: IVIG or anti-Rho(D) immunoglobulin

Therapy for ITP Refractory to First-Line or Persistent/Chronic ITP

• TPO-RAs (e.g. Romiplostim, Eltrombopag)
• Rituximab
• Splenectomy
  • Indications:
    • Treatment resistent thrombocytopenia lasting >12 months
    • Severe bleeding refractory to other treatment
    • Spleen should be confirmed as primary site of platelet breakdown using radioactively labeled thrombocytes if possible

Additional Flashcards

Suspect {{c1::ITP}} in a child with thrombocytpoenia and petechiae following a viral illness

- What is the emergency management for ITP once haemostatic control is achieved?

{{c1::Corticosteroids}}
{{c1::IVIG}}
{{c1::Platelet transfusions as needed}}

First line therapy for ITP is with {{c1::corticosteroids (e.g. dexamethasone or prednisone)}}
Indicated for:
- Adults with platelet count $<\pu{30,000 count // mm3}$
- Patients with significant non-life-threatening mucosal bleeding (e.g. severe epistaxis)
- Symptoms impacting quality of life

Footnotes

Footnotes

1. Advised to avoid contact sports and other high-risk activities ↩