Platelet transfusions should be used prophylactically with discretion because they may lose their effectiveness with repeated use owing to the development of platelet alloantibodies. If thrombocytopenia is caused by increased platelet consumption, platelet transfusions should be reserved for management of life-threatening or CNS bleeding. A hemorrhagic disorder not associated with a systemic disease, which is typically chronic in adults but is usually acute and self-limited in children. In childhood ITP, viral antigen is thought to trigger synthesis of antibody that may react with viral antigen associated with the platelet surface. Diagnosis Physical examination is normal except for petechiae, purpura, and mucosal bleeding, which may be minimal or extensive.
Peripheral blood is normal except for reduced platelet numbers.
Bone marrow examination reveals normal or possibly increased numbers of megakaryocytes in an otherwise normal marrow. In the patient who responds, the platelet count will rise to normal within 2 to 6 wk. The corticosteroid dosage is then tapered. The efficacy of other drugs used in patients refractory to corticosteroids and splenectomy is unproven. Because the long-term clinical course of chronic ITP is unknown and because many patients have minimal morbidity despite chronic ITP, the relative benefits and risks of treatment must be weighed carefully.