Idiopathic thrombocytopenic purpura (ITP) is a bleeding condition in which the blood doesn't clot as it should. This is due to a low number of blood cell fragments called platelets. Platelets also are called thrombocytes which are made in your bone marrow along with other kinds of blood cells. Platelets stick together (clot) to seal small cuts or breaks on blood vessel walls and stop bleeding. "Idiopathic" means that the cause of the condition isn't known. "Thrombocytopenic" means there's a lower than normal number of platelets in the blood. "Purpura" refers to purple bruises caused by bleeding under the skin.
All information about ITP is provided by the National Heart, Lung, and Blood Institute as a part of the National Institutes of Health and the U.S. Department of Health and Human Services.