Idiopathic Thrombocytopenic Purpura (ITP)
Idiopathic Thrombocytopenic Purpura (ITP) was found in 5-Minute Clinical Consult which helps you diagnose, treat, and follow up on over 900 medical conditions seen in everyday practice.
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- Idiopathic thrombocytopenic purpura (ITP) is an acquired, isolated thrombocytopenia with platelet counts of <100 × 109/L caused by accelerated destruction and/or impaired thrombopoiesis by antiplatelet antibodies.
- ITP is classified by:
- Age: Adult or pediatric
- Duration: Newly diagnosed (<3 months), persistent, or chronic (>12 months)
- Whether it occurs in isolation or in association with other disorder: Primary (idiopathic) or secondary
- ITP is a relatively common disease of childhood that often follows viral infection or vaccination. Onset is within 1 week, and spontaneous resolution occurs within 2 months in 83% of patients.
- In adults, ITP is usually a chronic disease and spontaneous remission is rare (9% in 1 series) (1).
- System(s) affected: Heme, Lymphatic, Immunologic
- Synonym(s): Immune thrombocytopenia; Immune thrombocytopenic purpura; and Werlhof disease
- Peak age:
- Pediatric ITP: 2–4 years
- Chronic ITP: >50
- Uncommon in geriatric population
- Predominant gender:
- Pediatric ITP: Male = Female
- Chronic ITP: Female > Male (1.2–1.7:1)
Meta-analysis of 3 studies from Europe estimated incidence at:
- 1.9–6.4/100,000 children/year
- 3.3/100,000 adults/year (2)
- Based on insurance data, overall prevalence of 9.5/100,000 persons.
- Based on survey of hematologists in 2004:
- 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), 12.1/100,000 persons with average age of 55 (3)
- Autoimmune thrombocytopenia (e.g., Evan syndrome)
- Common variable immune deficiency
- Drug side effect (e.g., quinidine, gold, penicillin, procainamide, methyldopa, sulfamethoxazole)
- Infections: H. pylori, hepatitis C, HIV, varicella zoster
- Vaccination side effect
- Bone marrow transplantation side effect
- Connective tissue disease such as systemic lupus erythematosus, antiphospholipid antibody syndrome
- Lymphoproliferative disorders
- 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.
Commonly Associated Conditions
- Viral infections such as measles, rubella, varicella, influenza, and EBV
- Live virus vaccinations carry a lower risk than natural viral infection: 2.6 cases per 100,000 MMR vaccine doses vs. 6–1,200 per 100,000 cases of natural rubella or measles infections