This CME activity is intended for physicians, nurse practitioners, and physician assistants who care for children who are ill or injured. Specialists including pediatricians, emergency physicians, pediatric emergency physicians, and family practitioners will find this information particularly useful.
LEARNING OBJECTIVESAfter completion of this article, the reader will be able to: 1. Describe the pathophysiology of idiopathic thrombocytopenic purpura. 2. Recognize common bleeding manifestations of acute idiopathic thrombocytopenic purpura and learn the clinical grading scale used to estimate the severity of bleeding manifestations. 3. Discuss the management of acute idiopathic thrombocytopenic purpura and understand treatment strategies for life-threatening bleeding.I diopathic thrombocytopenic purpura (ITP) is an immunemediated illness that results in thrombocytopenia (platelet count <150 Â 10 9 /L) due to platelet destruction from autoantibodies. It is classified as acute or chronic in children depending on the duration of the illness. Acute ITP occurs most commonly in children between the ages of 1 and 10 years and resolves in less than 6 months. Chronic ITP, by definition, lasts longer than 6 months and more commonly occurs in children older than 9 years. Two recent studies reported that approximately half of children aged 10 to 18 years with acute ITP developed chronic ITP. 1,2 Overall, 75% of patients with acute ITP will have resolution of their thrombocytopenia with or without treatment 6 months after diagnosis.The presentation and management of a child with acute ITP are varied and dependent upon many factors, such as the age of the child and clinical symptoms at presentation. This review focuses on the diagnosis and management of acute ITP of childhood.
EPIDEMIOLOGY AND PATHOPHYSIOLOGYThe annual incidence of acute ITP is estimated to be 2.5 to 5 per 100,000 children. 3,4 The peak age for presentation is 5.5 years. 3,5 There are some data supporting seasonal changes with a peak occurrence in the spring or early summer. 3,5 This seasonal variation may be linked to occurrence of viral illnesses during the same period. A history of a preceding viral illness is commonly associated with the development of acute ITP. The thrombocytopenia noted at presentation is severe, defined as a platelet count less than 20 Â 10 9 /L in more than 75% of patients. [3][4][5] The cause of ITP is unknown. Up to 50% to 80% of children with ITP will have antiplatelet antibodies that react with major membrane glycoproteins. 6 These antibodies are produced by B cell-derived plasma cells. Most of these antibodies are of the immunoglobulin (Ig) G class and are directed against glycoprotein IIb/IIIa and/or Ib/IX. 6-10 Platelet antibody complexes are cleared more rapidly by macrophages from the spleen and liver, resulting in thrombocytopenia. It remains to be elucidated what other critical factors play a role in the development of acute ITP such as the contribution of T-cell dysregulation and why some children go on to develop chronic au...