Immune thrombocytopenic purpura (ITP) is an acquired autoimmune disorder characterized by accelerated platelet destruction and suboptimal platelet production. It occurs in both adults and children. ITP can be classified based on the duration of the illness. Chronic ITP is defined as thrombocytopenia persisting for longer than 12 months following the initial diagnosis. Approximately 20%~25% of children with ITP become chronic ITP. Many of these children do not require specific platelet-enhancing therapy, and some enter spontaneous remission in subsequent years. Only 5%~10% of pediatric ITP patients have severe, chronic, and/or refractory disease and require platelet-enhancing therapy. New thrombopoietin (TPO) receptor agonists that stimulate platelet production are now approved for treating adults with chronic ITP, and are being studied for pediatric patients with some preliminary encouraging reports.

免疫性血小板低下紫斑症是一種後天自體免疫疾病，伴隨著血小板破壞增加與製造減少。此一疾病可以發生在成人或兒童身上。持續超過十二個月以上的血小板低下稱為慢性血小板低下紫斑症。大約只有20% 到25% 的兒童患者會成為慢性患者，而其中大多數的病童只需追蹤而不需要特殊的治療，只有5% 到10% 的病童屬於嚴重慢性/ 復發性免疫性血小板低下紫斑症而需要接受治療，新一代的血小板生成激素受體促進物可以刺激血小板的製造，也已經被核准用來治療慢性免疫性血小板低下紫斑症的成人患者，此類藥物在兒童患者的使用正在進行研究當中，而目前初步的報告顯示也有治療效果。