Immune thrombocytopenic purpura (ITP) is an autoimmune disease characterized by a low platelet count, purpura, and hemorrhagic episodes caused by antiplatelet autoantibodies. The diagnosis is typically made by excluding the known causes of thrombocytopenia. IgG autoantibodies sensitize the circulating platelets. It leads to the accelerated removal of these cells by antigen-presenting cells (macrophages) of the spleen and sometimes the liver or other components of the monocyte-macrophage system. The bone marrow compensates for platelet destruction by increasing platelet production. ITP most often occurs in healthy children and young adults within a few weeks following a viral infection.
ITP is usually manageable with immunosuppressive therapy. An identical form of autoimmune thrombocytopenia can also be associated with chronic lymphocytic leukemia, lymphomas, SLE, infectious mononucleosis, and other bacterial and viral infections. Certain drugs can also cause immune thrombocytopenia indistinguishable from ITP. Most children have spontaneous remission within a few weeks or months, and splenectomy is rarely needed. However, young adults rarely have spontaneous remissions necessitating splenectomy within the first few months after diagnosis.
The International Working Group on ITP defines ITP according to the following clinical phases. These are as follows:
Newly diagnosed ITP is in the first three months post-diagnosis.
Persistent ITP is for 3-12 months.
Chronic ITP is for > 12 months.
Refractory ITP is the failure of splenectomy.
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