Idiopathic thrombocytopenic purpura
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"immune thrombocytopenia" AND management
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Idiopathic Thrombocytopenic Purpura (ITP)
Also called immune thrombocytopenia or primary immune thrombocytopenic purpura, ITP is an autoimmune disorder in which antiplatelet IgG autoantibodies target specific platelet membrane glycoproteins (primarily GPIIb/IIIa and GPIb/IX), causing accelerated platelet destruction predominantly in the spleen, and in some patients, impaired megakaryocyte platelet production. The old term "idiopathic" is now largely replaced by "immune" to reflect the understood pathogenesis.
Pathogenesis
The traditional model implicates autoantibody-mediated destruction, but the full picture is more complex:
- IgG autoantibodies coat platelets -> Fc receptor-mediated phagocytosis in the spleen and liver
- T-cell-mediated (including CD8+ cytotoxic T cell) direct platelet destruction
- Impaired megakaryocyte platelet production - evidenced by the fact that TPO receptor agonists are effective in raising counts
- Up to 50% of ITP patients have no detectable antiplatelet antibodies, supporting additional non-antibody mechanisms
- Molecular mimicry plays a role in post-infectious cases; links exist with HIV, hepatitis C, and Helicobacter pylori
(Mulholland & Greenfield's Surgery, Henry's Clinical Diagnosis and Management)
Classification
| Type | Features |
|---|---|
| Newly diagnosed | Duration <3 months from diagnosis |
| Persistent | Duration 3-12 months |
| Chronic | Duration >12 months (or >6 months in children) |
| Primary (idiopathic) | No underlying cause identified |
| Secondary | Associated with SLE, CLL, Hodgkin's disease, HIV, HCV, H. pylori, drugs |
Epidemiology
- Adult form: predominantly females aged 15-50 years; gradual onset, chronic course
- Childhood form: equal sex distribution; typically presents before age 5; acute onset after viral illness; >80% are self-limited and resolve within 6 months; life-threatening bleed risk <0.5%
- Two peaks in adults: ages 20-30 (female predominance) and after age 60 (no sex difference)
(Bailey & Love's Surgery 28e; Tintinalli's Emergency Medicine; Mulholland & Greenfield's Surgery)
Clinical Features
- Petechiae and ecchymoses on skin and mucous membranes (positive tourniquet test)
- Easy bruising, epistaxis, gingival bleeding, menorrhagia, prolonged wound bleeding
- GI and urinary tract hemorrhage - rare
- Intracranial hemorrhage - uncommon but the most frequent cause of death
- Spleen is palpable in <10% of patients - gross splenomegaly should suggest an alternative diagnosis
- Fatigue is a common presenting complaint alongside mucocutaneous bleeding
Investigations
| Test | Finding |
|---|---|
| Platelet count | Reduced, usually <60 x 10⁹/L; diagnosis threshold <100,000/μL |
| Peripheral smear | Reduced platelets, otherwise normal morphology; large platelets (young platelets) |
| Coagulation studies (PT, aPTT) | Normal |
| Bone marrow aspirate | Plentiful megakaryocytes (normal to increased) |
| Antiplatelet antibodies | Detectable in only ~60% - not recommended for routine diagnosis |
| Bleeding time | Not helpful diagnostically |
- ITP is a diagnosis of exclusion - other causes must be ruled out
- Bone marrow biopsy is not part of routine evaluation; reserve for atypical presentations or before starting steroids if leukemia/aplastic anemia cannot be excluded clinically
(Bailey & Love's Surgery 28e; Henry's Clinical Diagnosis and Management)
Treatment
Children
- Most cases are self-limited and require watchful waiting
- Activity restriction and avoidance of antiplatelet medications for all
- Admit if platelet count <20,000/mm³, IV treatment needed, or spontaneous bleeding
Pharmacologic options (if treatment needed):
- Corticosteroids: prednisone 2 mg/kg/day x21 days; or methylprednisolone 30 mg/kg/day x4 days; or dexamethasone 20 mg/m²/day x4 days. Exclude leukemia/aplastic anemia before starting steroids
- IVIG 1 g/kg/day - superior to steroids for rapid platelet count improvement
- Anti-Rh(D) immunoglobulin 50-75 mcg/kg - only in Rh-positive patients; admit for risk of severe intravascular hemolysis; pretreat with acetaminophen + diphenhydramine
- Life-threatening hemorrhage: single-donor platelet transfusion (2-3x normal dose) + IV methylprednisolone + IVIG or anti-Rh(D)
Adults (Management Tiers)
First line:
- Corticosteroids (longer courses preferred over shorter)
- IVIG 1 g/kg (may repeat) or anti-D immunoglobulin (Rh-positive patients only)
Second line (30-40% of patients relapse after first-line):
- Splenectomy - up to two-thirds of patients cured; 15% improved; response to steroids predicts good response to splenectomy
- Rituximab (anti-CD20 monoclonal antibody) 375 mg/m² IV weekly x4 weeks
- TPO receptor agonists (eltrombopag, romiplostim) - approved for refractory ITP
- Immunosuppressive agents
Third line (refractory to first + second line):
- TPO receptor agonists
- Combination of first + second line therapies
- Combination chemotherapy
(Schwartz's Principles of Surgery 11e; Washington Manual; Mulholland & Greenfield's Surgery)
Splenectomy - Key Points
- Laparoscopic splenectomy is now the mainstay approach (spleen is usually normal to slightly enlarged and not friable)
- Essential to identify and remove splenunculi (accessory spleens) - they can enlarge and cause relapse
- Platelet transfusion in the acute setting is generally withheld until splenic vessels are controlled (transfused platelets will be rapidly destroyed by circulating autoantibodies)
- Up to 2/3 cured, 15% improved by surgery
Recent Evidence (2024-2026)
Three recent systematic reviews are noteworthy:
- A 2025 network meta-analysis (PMID: 40547032) compared rhTPO, romiplostim, and eltrombopag in pediatric ITP, supporting TPO receptor agonist use in refractory childhood disease.
- A 2025 meta-analysis (PMID: 41382219) evaluated dapsone in adult ITP as a second-line agent.
- A 2025 systematic review (PMID: 39552264) addressed management of critical bleeds in ITP patients.
These are consistent with the textbook framework and do not overturn existing management principles.
Sources: Bailey & Love's Short Practice of Surgery 28e | Schwartz's Principles of Surgery 11e | Tintinalli's Emergency Medicine | Mulholland & Greenfield's Surgery 7e | Henry's Clinical Diagnosis and Management by Laboratory Methods | Washington Manual of Medical Therapeutics
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