Idiopathic thrombotic thrombocytopenic purpura: strongest risk factor for relapse from remission is having had a relapse

BACKGROUND Thrombotic thrombocytopenic purpura (TTP) is a rare, episodic clinical syndrome involving the production of thrombi in the microvasculature accompanied by thrombocytopenia and symptoms of organ ischemia. Idiopathic TTP develops when a patient produces antibodies that react with the protease ADAMTS13. The course after an episode is unpredictable; patients may relapse frequently or never. There is no laboratory value that can reliably predict potential relapse. STUDY DESIGN AND METHODS To assess diagnostic and predictive values for risk of relapse, plasma samples from 27 patients with idiopathic TTP in remission were analyzed for anti-ADAMTS13 immunoglobulin (Ig)G, ADAMTS13 activit…