Idiopathic or Immune Thrombocytopenic Purpura (ITP) is the condition of having an abnormally low platelet count of unknown cause which can increase the risk of bleeding and result in a rash, called purpura, caused by spontaneous bleeding under the skin.

ITP often has no obvious symptoms and so may be discovered incidentally. Diagnosis is usually by a test which measures different types of blood cells. In some situations a bone marrow biopsy may be necessary to eliminate other reasons for a low platelet count.

Treatment may not be necessary in mild cases, but those patients with very low platelet counts or significant bleeding may require treatment with steroids, intravenous immunoglobulin or stronger drugs that suppress the immune system