Thrombotic thrombocytopenic purpura (TTP) is a blood disordercharacterized by low platelets (i.e., thrombocytopenia), small areas of bleeding under the skin (i.e., purpura), low red blood cell count, and hemolytic anemia. TTP causes blood clots (thrombi) to form in small blood vessels throughout the body. These clots can cause serious medical problems if they block vessels and decrease or stop blood flow to organssuch as the brain, kidneys, and heart. Complications may include neurological problems (such as personality changes, headaches, confusion, and slurred speech), fever, abnormal kidney function, abdominal pain, and heart problems. Hemolytic anemia can lead to paleness, yellowing of the eyes and skin (jaundice), fatigue, shortness of breath, and a rapid heart rate. Acquired TTP usually begins in adulthood, but can affect children. An episode of TTP usually occurs suddenly and lasts for days or weeks, but it may continue for months. Relapses (or flareups) can occur in up to 60% of people who have the acquired TTP. Acquired TTP is caused when a person’s body mistakingly makes antibodies that block the activity of the ADAMTS13 enzyme. THe ADAMTS13 enzyme normally helps control the activity of certain blood clotting factors. Treatment includes plasma exchange and in some cases may also include corticosteroid therapy or rituximab.