Immune Thrombocytopenic Purpura

Discipline : Haematology

Definition

Can be classified by aetiology:

Primary : autoimmune disorder characterised by isolated thrombocytopenia (most common)

Secondary : secondary to identifiable trigger: - Autoimmune disorders : SLE, 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
• highest prevalence <5 years old; typically self-limiting after viral infection; 80% resolve in 12 months
• 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@1709712278047
• Clinical features can correlate with platelet count; but most patients are asymptomatic:

• Minor mucocutaneous bleeding is possible:
  • Subcutaneous: bruising, petechiae, purpura
  • Mucosal: mild epistaxis, gingival bleeding

Investigations

CBC : Typically <$100,000\frac{\mathrm{count}}{\mathrm{m}{\mathrm{m}}^3}$

Coagulation panel is usually normal (unless secondary)

Bleeding time may be prolonged

Consider additional investigations for secondary causes: (e.g. HIV and HCV screening)

Bone marrow biopsy : normal or ↑ megakaryocytes

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

Emergenct 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

When to suspect ITP

Text

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

Source

Amboss: Immune thrombocytopenia. Accessed 6 March 2023 available at: https://next.amboss.com/us/article/8q0OZh#Ld8fe0f824fb313404f48b4e9850945ec

Emergency management

Text

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

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

Extra

If ⌀ response consider thrombopoietin receptor agonist (TPO-RA)

Source

Amboss: Immune thrombocytopenia. Accessed 6 March 2023 available at: https://next.amboss.com/us/article/8q0OZh#Ld8fe0f824fb313404f48b4e9850945ec

One by one

y

First line therapy

Text

First line therapy for ITP is with c1::corticosteroids (e.g. dexamethasone or prednisone)

Extra

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

Source

Amboss: Immune thrombocytopenia. Accessed 6 March 2023 available at: https://next.amboss.com/us/article/8q0OZh#Ld8fe0f824fb313404f48b4e9850945ec

Footnotes

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