Autoimmune thrombocytopenic purpura

Immune thrombocytopenia purpura (ITP), also known as idiopathic thrombocytopenic purpura, is a type of thrombocytopenic purpura defined as isolated low platelet count with normal bone marrow and the absence of other causes of low platelets. It causes a characteristic purpuric rash and an increased tendency to bleed. Two distinct clinical syndromes manifest as an acute condition in children and a chronic condition in adults. The acute form often follows an infection and has a spontaneous resolution within two months. Chronic immune thrombocytopenia persists longer than six months with a specific cause being unknown.Petechiae on the lower extremitiesOral petechiae/purpura - lower lipPetechia on the tongue in a person with platelets of 3 due to ITPPetechia of the lower leg in a person with platelets of 3 due to ITP Immune thrombocytopenia purpura (ITP), also known as idiopathic thrombocytopenic purpura, is a type of thrombocytopenic purpura defined as isolated low platelet count with normal bone marrow and the absence of other causes of low platelets. It causes a characteristic purpuric rash and an increased tendency to bleed. Two distinct clinical syndromes manifest as an acute condition in children and a chronic condition in adults. The acute form often follows an infection and has a spontaneous resolution within two months. Chronic immune thrombocytopenia persists longer than six months with a specific cause being unknown. ITP is an autoimmune disease with antibodies detectable against several platelet surface antigens. ITP is diagnosed by a low platelet count in a complete blood count (a common blood test). However, since the diagnosis depends on the exclusion of other causes of a low platelet count, additional investigations (such as a bone marrow biopsy) may be necessary in some cases. In mild cases, only careful observation may be required but very low counts or significant bleeding may prompt treatment with corticosteroids, intravenous immunoglobulin, anti-D immunoglobulin, or immunosuppressive medications. Refractory ITP (not responsive to conventional treatment) may require splenectomy, the surgical removal of the spleen. Platelet transfusions may be used in severe bleeding together with a very low count. Sometimes the body may compensate by making abnormally large platelets. Signs include the spontaneous formation of bruises (purpura) and petechiae (tiny bruises), especially on the extremities, bleeding from the nostrils and/or gums, and menorrhagia (excessive menstrual bleeding), any of which may occur if the platelet count is below 20,000 per μl. A very low count (<10,000 per μl) may result in the spontaneous formation of hematomas (blood masses) in the mouth or on other mucous membranes. Bleeding time from minor lacerations or abrasions is usually prolonged. Serious and possibly fatal complications due to extremely low counts (<5,000 per μl) include subarachnoid or intracerebral hemorrhage (bleeding inside the skull or brain), lower gastrointestinal bleeding or other internal bleeding. An ITP patient with an extremely low count is vulnerable to internal bleeding caused by blunt abdominal trauma, as might be experienced in a motor vehicle crash. These complications are not likely when the platelet count is above 20,000 per μl. In approximately 60 percent of cases, antibodies against platelets can be detected.  Most often these antibodies are against platelet membrane glycoproteins IIb-IIIa or Ib-IX, and are of the immunoglobulin G (IgG) type. The Harrington–Hollingsworth experiment, established the immune pathogenesis of ITP. The coating of platelets with IgG renders them susceptible to opsonization and phagocytosis by splenic macrophages, as well by Kupffer cells in the liver.  The IgG autoantibodies are also thought to damage megakaryocytes, the precursor cells to platelets, although this is believed to contribute only slightly to the decrease in platelet numbers.  Recent research now indicates that impaired production of the glycoprotein hormone thrombopoietin, which is the stimulant for platelet production, may be a contributing factor to the reduction in circulating platelets.  This observation has led to the development of a class of ITP-targeted medications referred to as thrombopoietin receptor agonists. The stimulus for auto-antibody production in ITP is probably abnormal T cell activity.  Preliminary findings suggest that these T cells can be influenced by medications that target B cells, such as rituximab.