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Immune thrombocytopenia

Last updated: May 10, 2021

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Immune thrombocytopenia (ITP) is a type of thrombocytopenia involving the formation of autoantibodies against platelets. ITP may be a primary disease or occur secondary to a known trigger (e.g., SLE, HIV, hepatitis C, medications). It is commonly seen in children as a self-limiting illness following a viral infection, and in adults as a chronic illness. Most patients are asymptomatic, however, patients may occasionally present with minor mucocutaneous bleeding (e.g., petechiae, purpura, epistaxis) or, rarely, with severe bleeding (e.g., gastrointestinal or intracranial hemorrhage). Treatment recommendations vary depending on the presence and severity of symptoms. First-line medical therapy consists of corticosteroids, IVIG, or anti-D immunoglobulin, and is indicated for patients with non-life-threatening symptoms affecting their quality-of-life, and for adults with little-to-no symptoms and platelet counts below 30,000/mm3. Children with little-to-no symptoms can typically be managed with observation alone regardless of platelet count. Second-line treatments (i.e., thrombopoietin receptor agonists, rituximab, splenectomy) be required for refractory, persistent or chronic cases. Patients with life-threatening hemorrhage, neurological symptoms, or those requiring urgent surgical interventions should receive immediate combination medical therapy (i.e., corticosteroids plus IVIG) along with platelet transfusions and hemostatic control interventions when necessary.

See also “Thrombocytopenia.”

Immune thrombocytopenia has previously been referred to as idiopathic thrombocytopenic purpura, however, this term is outdated.

  • Primary immune thrombocytopenia: : an autoimmune disorder characterized by isolated thrombocytopenia (< 100,000/mm3) with no known precipitating cause [1]
  • Secondary immune thrombocytopenia: an autoimmune hematologic disorder causing isolated thrombocytopenia that is secondary to an identifiable trigger (see “Etiology”).
  • Newly diagnosed ITP: all cases within the first 3 months of diagnosis [1]
  • Persistent ITP: ITP lasting 3–12 months
  • Chronic ITP: ITP lasting > 12 months
  • Prevalence: up to ∼ 10 per 100,000 [2][3]
  • > [2]
  • Children
    • Highest prevalence in children < 5 years of age [2]
    • Typically self-limiting after a viral infection; 80% of cases resolve within 12 months [4]
  • Adults
    • Highest prevalence in individuals > 55 years of age [2]
    • 80% of patients develop chronic ITP. [4]
    • An incidental finding on a routine CBC in 25% of cases [5]

Epidemiological data refers to the US, unless otherwise specified.

Antiplatelet antibodies (mostly IgG directed against, e.g., GpIIb/IIIa, GpIb/IX) bind to surface proteins on platelets sequestration by spleen and liver platelet count bone marrow megakaryocytes and platelet production increase in response (in most cases) [7]

Clinical features can correlate with platelet count (see also “Clinical features of thrombocytopenia” and “Clinical features of bleeding disorders”).

Splenomegaly is very unusual in ITP and makes other diagnoses more likely!

There should be suspicion for ITP in a child with thrombocytopenia and petechiae following a viral illness!

ITP is a diagnosis of exclusion; patients typically have a low platelet count with no other abnormalities. [4]

Laboratory studies [8][9][10]

Routine

Additional investigations

See “Differential diagnosis of platelet disorders.”

The differential diagnoses listed here are not exhaustive.

Approach

These recommendations are consistent with the 2019 American Society of Hematology ITP guidelines and the 2019 International Consensus Report on primary ITP investigation and management. [12][13]

Management approach for ITP [12][13]
Management Newly diagnosed ITP Persistent or chronic ITP
All patients
  • Identify and treat underlying causes.
  • Consider stopping medications that impair platelet function, e.g., NSAIDs. [14]

Patients requiring emergency treatment:

  • Life-threatening bleeding
  • Acute neurological features
  • Anticipated urgent surgery or invasive procedure

Patients with:

  • No symptoms
  • Only minor mucocutaneous bleeding
  • Consider subsequent therapeutic options depending on individual patient factors.

Patients with:

Significant non-life-threatening mucosal bleeding

Symptoms impacting quality-of-life

  • First-line medical therapy
    • Indicated for adults
    • Can be considered in children
  • Consider subsequent therapeutic options if refractory to first-line medical therapy.
Disposition
  • Hospital admission should be considered for:
    • Patients requiring emergency treatment
    • Patients with significant functional impairment or risk of significant hemorrhage
    • Asymptomatic or minimally symptomatic adults with platelet counts < 20,000/mm3
  • Outpatient management with hematology follow-up is appropriate for:
  • Can typically be managed as an outpatient, regardless of platelet level
  • Consider hospital admission if significant functional impairment or need for emergency treatment.

Patients that can be managed as outpatients should receive expedited hematology follow-up within 24–72 hours. [12]

Conservative management [12][13]

  • Indications for observation
    • Children: no symptoms or only mild mucocutaneous bleeding with any platelet count
    • Adults: no symptoms or minor mucocutaneous bleeding with a platelet count of ≥ 30,000/mm3
  • All patients: Refer to hematology for regular monitoring and counseling on bleeding risks.

First-line medical therapy [12][13]

Anti-Rho(D) immunoglobulin can cause potentially fatal intravascular hemolysis in patients with ITP. Close monitoring is recommended.

Subsequent therapeutic options [13]

The following options should be considered in consultation with a specialist for patients with newly-diagnosed ITP refractory to first-line medical therapy, or persistent/chronic ITP.

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  2. Neunert C, Lim W, Crowther M, et al. The American Society of Hematology 2011 evidence-based practice guideline for immune thrombocytopenia. 117. 2011; 16 (4190-4207). doi: 10.1182/blood-2010-08-302984 . | Open in Read by QxMD
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