Thrombocytopenic Purpura, Idiopathic (ITP)

Key Features

Essentials of Diagnosis

• Otherwise healthy child

• Decreased platelet count

• Petechiae, ecchymoses

General Considerations

• Most common bleeding disorder of childhood

• Occurs most frequently in children aged 2–5 years

• Often follows infection with viruses, such as

  • Rubella

  • Varicella

  • Measles

  • Parvovirus

  • Influenza

  • Epstein-Barr virus (EBV)

  • Acute and chronic HIV

• Most patients recover spontaneously within a few months

• Chronic ITP (> 12 months' duration) occurs in 10–20% of affected patients

Clinical Findings

• Sudden onset, with appearance of multiple petechiae and ecchymoses

• Epistaxis is common at presentation

• Rarely, concurrent infection with EBV or CMV may cause hepatosplenomegaly or lymphadenopathy, simulating acute leukemia

Diagnosis

• Platelet count is markedly reduced (usually < 50,000/μL and often < 10,000/μL)

• Platelets are frequently large on peripheral blood smear, suggesting accelerated production of new platelets

• Platelet-associated IgG or IgM, or both, may be demonstrated on the patient's platelets or in the serum

• Prothrombin time and activated partial thromboplastin time are normal

• White blood count and differential are normal

• Hemoglobin concentration is preserved unless hemorrhage has been significant

• Number of megakaryocytes is increased

• Erythroid and myeloid cellularity is normal

Treatment

General Measures

• Observation is recommended for most children in the absence of bleeding regardless of platelet count

• Food and medications (eg, aspirin and nonsteroidal anti-inflammatory drugs) that compromise platelet function should be avoided

• Bleeding precautions (eg, restriction from physical contact activities and use of helmets) should be observed

Medications

• Corticosteroids

  • Short course may benefit patients with clinically significant but non–life-threatening bleeding and those with a platelet count of less than 10,000/μL

  • Dosing

    • Initial dose of prednisone 3–5 mg/kg/d for 3–7 days may lead to faster count recovery

    • Additional prednisone not given unless significant bleeding recurs, at which time smallest dose that achieves resolution of bleeding episode is administered (usually 2.5–5 mg twice daily)

  • Long-term use should be avoided because of toxicity

• Intravenous immunoglobulin (IVIg)

  • Treatment of choice for severe, acute bleeding

  • May be used as an alternative or adjunct to corticosteroid treatment

  • A single dose of 0.8–1 g/kg has been recommended

  • Platelets may be given simultaneously during life-threatening hemorrhage but are rapidly destroyed

• Anti-Rh(D) immunoglobulin

  • Effective only in Rh(+) patients with a functional spleen who are DAT negative

  • At doses of 50–75 μg/kg, approximately 80% of Rh(+) children with acute or chronic ITP respond

  • However, there is no clear difference between anti-D and IVIg in the time to reach the end point of achieving a platelet count of 20 × 10⁹/L

Surgery

• Splenectomy

  • Produces a complete response in 70% and partial response in 20% of children

  • Should be considered only after persistence of significant thrombocytopenia for more than 12 months, and the failure ...