Thrombocytopenia in Children

Background

• Thrombocytopenia in children is defined as a platelet count < 150 × 10⁹/L.
• Thrombocytopenia should be differentiated from pseudothrombocytopenia which is an artificially low platelet count that can occur in samples anticoagulated with EDTA or sometimes other anticoagulants. An artificially low platelet count can also occur in neonatal blood samples collected via heel stick and some other settings.
• Thrombocytopenia can be categorized as inherited or acquired, and can be differentiated by the underlying mechanism, either by decreased production or increased destruction through either a consumptive process or extravascular loss.

Table 1. Causes of Thrombocytopenia in Children

• Unless there is platelet dysfunction, signs and symptoms of bleeding generally do not occur until platelet count is below 50 × 10⁹/L. Spontaneous bleeding generally does not occur if platelet counts are above 5-10 × 10⁹/L.

Evaluation

• Perform a complete history and physical exam.
  • Obtain vital signs, including heart rate, respiratory rate, blood pressure, and oxygen saturation. Assess for bleeding and hemodynamic stability.
  • Ask about history of bleeding including epistaxis, oropharyngeal bleeding, hematemesis, blood in stool, or heavy menstrual bleeding. Also ask about bleeding in relation to eruption of teeth and perisurgical bleeding, including with dental work.
  • Also obtain complete family history including family history of bleeding, easy bruising, heavy menstrual bleeding, or known platelet or bleeding disorders.
• Obtain a complete blood count and peripheral blood smear. Confirm low platelet count via blood smear to rule out pseudothrombocytopenia.
• A child with any additional cytopenia and/or immature cells on blood smear should be evaluated for leukemia; see Acute Lymphoblastic Leukemia/Lymphoblastic Lymphoma (ALL/LBL) in Children, Acute Myeloid Leukemia (AML), or Chronic Myeloid Leukemia (CML) for additional information. Thrombocytopenia may be the consequence of a neoplastic infiltration of the bone marrow causing reduction in platelet production.
• Consider primary thrombocytopenia (ITP) and familial thrombocytopenia after ruling out secondary causes of ITP.
• If familial thrombocytopenia is suspected, additional testing may include coagulation screen, platelet function assays, genetic testing, and possibly, but less often, bone marrow analysis.
• Consult with hematologist if thrombocytopenia presents with additional cytopenias, there is a history of ongoing bleeding, thrombocytopenia is persistent, patient is diagnosed with ITP and has severe bleeding, or patient is scheduled for surgery and has either a personal or family history of abnormal bleeding.

Management

• Treatment depends on the underlying cause of thrombocytopenia. Treatment goals include controlling bleeding when present, minimizing risk of bleeding including reducing risk of bleeding during surgery, and managing the underlying cause of thrombocytopenia.
• For most stable children, consider prophylactic transfusion when platelet count is < 10 × 10⁹/L, except for children with immune thrombocytopenia (ITP), thrombotic thrombocytopenic purpura (TTP), or heparin-induced thrombocytopenia (HIT) who should only be transfused for life-threatening bleeding (Weak Recommendation).
• Otherwise, suggested thresholds for platelet transfusion vary depending on condition and clinical scenario.