Thrombotic thrombocytopenic purpura and Graves disease.

Patients with an autoimmune disease have a propensity for development of a second autoimmune disease. We report the first instance of a patient with both idiopathic thrombotic thrombocytopenic purpura (TTP) and Graves disease. The TTP remitted with a combination of plasmapheresis and prednisone. Methimazole led to sustained remission of the hyperthyroid state within 6 weeks. Although hyperthyroidism may induce immune imbalance causing autoimmunity, it is unclear if this influenced the development of TTP in our patient and if treatment of hyperthyroidism alone could have resulted in the cure of both diseases.