Residency · Residency · Medicine Pediatrics
Thrombocytopenia and ITP in Children Versus Adults
Overview
Thrombocytopenia: platelet count <150,000/mcL. The differential diagnosis and management of thrombocytopenia differ substantially between children and adults. Immune thrombocytopenic purpura (ITP) is the most common cause of isolated thrombocytopenia in otherwise well children. In adults, the differential is broader and more often includes serious underlying pathology.
Classification of Thrombocytopenia by Mechanism
Decreased Production
Bone marrow failure: aplastic anemia, Fanconi anemia (congenital, often presents in childhood) Bone marrow infiltration: leukemia, lymphoma, metastatic disease, myelofibrosis. Nutritional deficiency: B12, folate, severe iron deficiency. Medications: chemotherapy, valproic acid, linezolid. Viral suppression: HIV, hepatitis C, EBV, parvovirus B19. Congenital thrombocytopenias: Wiskott-Aldrich syndrome (small platelets, eczema, immunodeficiency), Bernard-Soulier (giant platelets), MYH9-related disorders.
Increased Destruction
Immune-mediated: ITP, drug-induced (heparin, quinine, vancomycin), SLE, antiphospholipid syndrome. Non-immune consumption: DIC, TTP, HUS, HELLP, mechanical (ECMO, prosthetic valves) Infection-associated: sepsis, malaria, dengue.
Sequestration
Hypersplenism from portal hypertension, hematologic malignancies, storage diseases (Gaucher)
Dilutional
Massive transfusion, large-volume fluid resuscitation.
<image>Algorithmic approach to thrombocytopenia showing initial assessment with CBC, peripheral smear, and reticulocyte count, then branching by mechanism: decreased production versus increased destruction versus sequestration</image>
Immune Thrombocytopenic Purpura (ITP)
| Feature | Pediatric ITP | Adult ITP |
|---|---|---|
| Peak age | 2-5 years | Increases with age |
| Sex ratio | Equal | Female > Male (2:1) |
| Onset | Sudden (post-viral) | Insidious |
| Spontaneous remission | ~80% within 6-12 months | Uncommon |
| Course | Usually acute, self-limited | Usually chronic |
| Treatment threshold | Observation preferred unless significant bleeding | Platelets <30,000 or significant bleeding |
| Bone marrow biopsy | Not required for typical presentation | Consider if atypical or age >60 |
Pediatric ITP
Epidemiology: peak age 2-5 years, equal sex distribution, incidence 4-5 per 100,000 children/year. Pathophysiology: autoantibodies (IgG) against platelet glycoproteins (GPIIb/IIIa, GPIb/IX); often triggered by preceding viral illness or vaccination. Presentation: sudden onset of petechiae, purpura, and mucosal bleeding in an otherwise well child; no hepatosplenomegaly, no lymphadenopathy, no systemic symptoms. Course: ~80% resolve spontaneously within 6-12 months regardless of treatment; 20% become chronic (>12 months)
Adult ITP
Epidemiology: more common in women (2:1), incidence increases with age; often chronic from onset. Pathophysiology: same autoantibody mechanism but more complex — includes T-cell mediated platelet destruction and impaired megakaryopoiesis. Presentation: more insidious onset; may have incidental finding on CBC or gradual increase in bleeding symptoms. Course: spontaneous remission is uncommon; most require treatment; higher risk of clinically significant bleeding than children.
Diagnosis of ITP
ITP is a diagnosis of exclusion — no confirmatory test. CBC: isolated thrombocytopenia with normal WBC and hemoglobin (unless concurrent iron deficiency from bleeding) Peripheral smear: large platelets, no schistocytes, no blasts, no dysplasia — MANDATORY to exclude other diagnoses. Additional testing: Children: typically none needed for classic presentation; bone marrow biopsy NOT required for typical ITP. Adults: HIV, hepatitis C, H. pylori, ANA, immunoglobulin levels, peripheral smear; direct antiglobulin test to rule out Evans syndrome; consider bone marrow biopsy if atypical features or age >60.
Management of ITP
Pediatric Management
Observation: preferred for most children, even with platelets <20,000, if no significant bleeding. ASH 2019 guidelines recommend observation over treatment for children with no or mild bleeding (skin manifestations only) regardless of platelet count. Activity restrictions: avoid contact sports and activities with high injury risk when platelets <50,000; no aspirin/NSAIDs. Indications for treatment: clinically significant mucosal bleeding (epistaxis, GI bleeding, menorrhagia), need for surgery, or rare life-threatening hemorrhage.
First-Line Treatment
Corticosteroids: prednisone 1-2 mg/kg/day for 5-7 days (short course preferred in children); dexamethasone 0.6 mg/kg/day x 4 days (adult: 40 mg/day x 4 days, may repeat in cycles) IVIG: 0.8-1 g/kg single dose; rapid platelet rise within 24-48 hours; preferred when rapid response needed (e.g., before surgery, significant bleeding) Anti-D immunoglobulin (WinRho): only for Rh-positive, non-splenectomized patients; risk of severe hemolysis (black box warning); less commonly used now.
Second-Line and Chronic ITP Treatment
Thrombopoietin receptor agonists (TPO-RAs): Eltrombopag (oral): approved for ages >= 1 year; 75% response rate. Romiplostim (subcutaneous weekly): approved for ages >= 1 year; stimulates megakaryopoiesis. Generally well-tolerated; risk of bone marrow reticulin fibrosis with long-term use (reversible) Rituximab: anti-CD20; initial response ~60%, but only ~20-30% sustain response at 5 years; off-label in children. Mycophenolate mofetil: steroid-sparing option for chronic ITP. Fostamatinib: SYK inhibitor; approved for adults with chronic ITP after failure of prior therapy.
Splenectomy
Reserved for chronic, refractory ITP failing multiple therapies. ~65-70% achieve durable remission. In children: delay until age >5 years to reduce overwhelming post-splenectomy infection (OPSI) risk. Pre-splenectomy: vaccinate against S. pneumoniae, N. meningitidis, H. influenzae type b. Post-splenectomy: lifelong penicillin prophylaxis in children (duration in adults debated)
<image>Treatment algorithm for ITP comparing pediatric and adult approaches from observation through first-line therapy, second-line agents including TPO receptor agonists, rituximab, and splenectomy</image>
Emergency Management of Severe Bleeding
Life-threatening bleeding (ICH, severe GI): extremely rare (<0.5% of children, <1-2% of adults) Multimodal approach: IV methylprednisolone + IVIG + platelet transfusion simultaneously. Platelet transfusions: give despite rapid destruction — they provide temporary hemostasis. Aminocaproic acid or tranexamic acid for mucosal bleeding. Emergency splenectomy may be considered if refractory. Recombinant activated factor VII (off-label) in refractory life-threatening bleeding.
Special Scenarios
ITP in Pregnancy
Must distinguish from gestational thrombocytopenia (platelet count usually >70,000, third trimester, no treatment needed) Also exclude preeclampsia/HELLP, TTP, DIC. Treatment: corticosteroids (avoid dexamethasone — crosses placenta) and IVIG. TPO-RAs: limited safety data in pregnancy. Neonatal thrombocytopenia occurs in 10-15% of infants born to mothers with ITP (usually mild)
Evans Syndrome
ITP combined with autoimmune hemolytic anemia (positive DAT) More common in children with underlying immune dysregulation. Higher risk of chronic course and treatment refractoriness. Screen for underlying primary immunodeficiency or autoimmune lymphoproliferative syndrome (ALPS)
Drug-Induced Thrombocytopenia
Heparin-induced thrombocytopenia (HIT): type II is immune-mediated, typically 5-14 days after heparin exposure; paradoxical thrombosis; 4T score for pre-test probability; confirm with anti-PF4/heparin antibodies and functional assay. Other drugs: quinine, vancomycin, trimethoprim-sulfamethoxazole, GPIIb/IIIa inhibitors. Management: stop offending drug; for HIT, initiate non-heparin anticoagulant (argatroban, bivalirudin)
<image>Comparison table of key features distinguishing ITP from other causes of thrombocytopenia including TTP-HUS, DIC, HIT, bone marrow failure, and drug-induced thrombocytopenia</image>
Clinical Pearls
A well-appearing child with sudden-onset petechiae and isolated thrombocytopenia almost always has ITP — avoid reflexive bone marrow biopsy. Always examine the peripheral smear: schistocytes suggest TMA (TTP/HUS), blasts suggest leukemia, giant platelets suggest inherited thrombocytopenia. In pediatric ITP, the platelet count does NOT predict bleeding — clinical bleeding assessment (mucosal vs. cutaneous only) guides treatment decisions. Adult ITP treatment threshold is generally platelet count <30,000 or significant bleeding; do not treat the number alone. Eltrombopag interacts with calcium, iron, and antacids — must be taken on empty stomach 2 hours from these substances. Consider secondary ITP causes in adults: check HIV, HCV, H. pylori (treatment of H. pylori can improve platelet count in endemic areas) Post-vaccination ITP in children is well-documented (especially MMR) but extremely rare and self-limited; benefits of vaccination far outweigh this risk.
References
- Neunert C, Terrell DR, Arnold DM, et al. American Society of Hematology 2019 Guidelines for Immune Thrombocytopenia. Blood Adv. 2019;3(23):3829-3866.
- Provan D, Arnold DM, Bussel JB, et al. Updated International Consensus Report on the Investigation and Management of Primary Immune Thrombocytopenia. Blood Adv. 2019;3(22):3780-3817.
- Cines DB, Bussel JB, Liebman HA, Luning Prak ET. The ITP Syndrome: Pathogenic and Clinical Diversity. Blood. 2009;113(26):6511-6521.
- Grainger JD, Thind D. A Practical Guide to the Management of Immune Thrombocytopenia in Childhood. Paediatr Drugs. 2019;21(4):289-301.
