The disease occurs when immune system cells, called lymphocytes, produce antibodies against platelets. Platelets are necessary for normal blood clotting. They clump together to plug small holes in damaged vessels. The presence of antibodies on platelets leads to their destruction in the spleen. A characteristic skin rash, easy bruising, abnormal menstrual bleeding, or sudden and severe loss of blood from the gastrointestinal tract may occur. Usually, no other abnormal findings are present. In children, the disease is sometimes preceded by a viral infection and usually runs its course without treatment. In adults, it is more often a chronic (long-term) disease and can follow a viral infection, certain drugs, pregnancy, or other immune disorders.
ITP affects women more frequently than men, and is more common in children than adults. Equal numbers of boys and girls are affected.
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