Immune Thrombocytopenia (ITP)

Immune Thrombocytopenia (ITP) is a topic covered in the 5-Minute Clinical Consult.

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Basics

Description

  • Immune thrombocytopenia (ITP) is a condition characterized by the immunologic destruction of normal platelets and/or impaired thrombopoiesis in response to an unknown stimulus.
  • It is defined as a platelet count <100 × 109/L, once other causes of thrombocytopenia have been ruled out (1).
  • ITP nomenclature:
    • Newly diagnosed (<3 months), persistent (3 to 12 months), and chronic (>12 months)
    • Primary when it presents in isolation; secondary when associated with other disorders
  • ITP is a relatively common disease of childhood that typically follows a viral infection. Onset is within 1 week, and spontaneous resolution occurs within 2 months in >80% of patients.
  • In adults, ITP is usually a chronic disease and spontaneous remission is rare.
  • Synonym(s): idiopathic thrombocytopenic purpura; immune thrombocytopenic purpura; and Werlhof disease

Epidemiology

  • Peak age
    • Pediatric ITP: 2 to 4 years
    • Chronic ITP: >50 years with incidence 2 times higher in persons 60 years than those <60 years of age
  • Predominant gender
    • Pediatric ITP: male = female
    • Chronic ITP: female > male (1.2 to 1.7:1)

Incidence
  • Pediatric acute ITP: 1.9 to 6.4/100,000 children/year (2)
  • Adult ITP: 1.6/100,000 per year (1)
Prevalence

Limited data. In one population (in Oklahoma) (3):

  • Overall prevalence of 11.2/100,000 persons
  • In children (<16 years): 8.1/100,000 with average age of 6 years
  • In adults (>16 years): 12.1/100,000 persons with average age of 55 years

Etiology and Pathophysiology

  • Accelerated platelet uptake and destruction by reticuloendothelial phagocytes results from action of IgG autoantibodies against platelet membrane glycoproteins IIb/IIIa. There is also cell-mediated platelet destruction by CD8+ T cells.
  • Autoantibodies interfere with megakaryocyte maturation, resulting in decreased production.

Risk Factors

  • Autoimmune thrombocytopenia (e.g., Evans syndrome)
  • Common variable immune deficiency (CVID)
  • Drug side effect (e.g., quinidine, vancomycin, penicillin, sulfonamides)
  • Infections: Helicobacter pylori, hepatitis C, HIV, CMV, varicella zoster, measles, rubella, influenza, EBV
  • Vaccination side effect. Live virus vaccinations carry a lower risk than natural viral infection: 2.6/100,000 cases MMR vaccine doses versus 6 to 1,200/100,000 cases of natural rubella or measles infections
  • Bone marrow transplantation side effect
  • Connective tissue disease, such as systemic lupus erythematosus, antiphospholipid antibody syndrome
  • Lymphoproliferative disorders

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Citation

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TY - ELEC T1 - Immune Thrombocytopenia (ITP) ID - 1688027 ED - Baldor,Robert A, ED - Domino,Frank J, ED - Golding,Jeremy, ED - Stephens,Mark B, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688027/all/Immune_Thrombocytopenia__ITP_ PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -