ITP, immune (idiopathic) thrombocytopenic purpura, is an autoimmune disease. In autoimmune diseases, the body mounts an immune attack toward one or more seemingly normal organ systems. In ITP, platelets are the target. They are marked as foreign by the immune system and eliminated in the spleen and sometimes, the liver. In addition to increased platelet destruction, some people with ITP also have impaired platelet production.
Platelets are relatively small, irregularly shaped components of our blood. They are required to maintain the integrity of our blood vessel walls and for blood to clot. Without a sufficient number of platelets, a person with ITP is subject to spontaneous bleeding or bruising.
People with ITP often have bruises or small purple spots on their skin (petechiae) where their blood has escaped from their veins or capillaries. Spontaneous bleeding can also occur in the mucus membranes on the inside of the mouth or in the gastro-intestinal tract. It is possible, with
a decreased number of platelets, to have a spontaneous cerebral hemorrhage. ITP is often accompanied by fatigue and sometimes depression.
Normal platelet counts range from 150,000 to 400,000 per microliter of blood. People with platelet counts under 10,000 have a severe case of ITP. 30,000 is sufficient for many to prevent a catastrophic bleed. Individual reactions to low platelet counts differ. Determining a safe platelet count is a decision to be made in consultation with an experienced treating physician.
The number of individuals in the United States with ITP has been estimated to be approximately 200,000. Our survey indicates that ITP occurs more frequently in women than men during childbearing years. It is usually a chronic problem. ITP in children occurs at about the same rate in boys and girls. It is frequently self-correcting but may become chronic. Adolescent ITP has more of the characteristics of adult ITP.
While most cases of ITP are controlled, it can be fatal in a small percentage of ITP patients.