Immune thrombocytopenic purpura (ITP), formerly known as idiopathic thrombocytopenic purpura, is a condition that develops secondary to immune-mediated destruction of platelets, resulting in thrombocytopenia (platelet count < 100,000/mm³). Immune thrombocytopenic purpura can be either primary or secondary due to drugs or underlying disease. The diagnosis is usually one of exclusion. Many patients with ITP are asymptomatic. When present, symptoms are primarily related to bleeding (e.g., bruising, petechiae, epistaxis), but fatigue is also common. The severity of thrombocytopenia in patients with ITP is variable. When platelet counts drop to < 20,000/mm³, the risk of serious bleeding increases. Treatment may include platelet transfusion, steroids, IV immune globulins, and/or splenectomy. Some cases remit spontaneously; others generally have a good prognosis with appropriate therapy.