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Thrombotic thrombocytopenic purpura (TTP or Moschcowitz syndrome) is a rare disorder of the blood-coagulation system, causing extensive microscopic clots to form in the small blood vessels throughout the body. These small blood clots, called thrombi, can damage many organs including the kidneys, heart and brain. In the era before effective treatment with plasma exchange, the fatality rate was about 90%. With plasma exchange, this has dropped to 10% at six months. Immunosuppressants, such as glucocorticoids, rituximab, cyclophosphamide, vincristine, or cyclosporine, may also be used if a relapse or recurrence follows plasma exchange. Most cases of TTP arise from inhibition of the enzyme ADAMTS13, a metalloprotease responsible for cleaving large multimers of von Willebrand factor (vWF) into smaller units. The increase in circulating multimers of vWF increase platelet adhesion to areas of endothelial injury, particularly at arteriole-capillary junctions. A rarer form of TTP, called Upshaw–Schulman syndrome, is genetically inherited as a dysfunction of ADAMTS13. If large vWF multimers persist, a tendency for increased coagulation exists. Red blood cells passing the microscopic clots are subjected to shear stress which damages their membranes, leading to rupture of red blood cells within blood vessels, which in turn leads to anaemia and schistocyte formation. Reduced blood flow due to thrombosis and cellular injury results in end organ damage. Current therapy is based on support and plasmapheresis to reduce circulating antibodies against ADAMTS13 and replenish blood levels of the enzyme.〔 ==Signs and symptoms== Classically, the following five features ("pentad") are indicative of TTP; in most cases, some of these are absent.〔 * Thrombocytopenia (low platelet count), leading to bruising or purpura * Microangiopathic hemolytic anemia (anemia, jaundice and a blood film featuring evidence of mechanical fragmentation of red blood cells) * Neurologic symptoms (fluctuating), such as hallucinations, bizarre behavior, delirium, stroke, or headaches * Kidney failure * Fever The symptoms of TTP may at first be subtle, starting with malaise, fever, headache, and sometimes diarrhea. As the condition progresses, clots (thrombi) form within blood vessels, and platelets (clotting cells) are consumed. Bruising, and rarely bleeding, results and may be spontaneous. The bruising often takes the form of purpura, while the most common site of bleeding, if it occurs, is from the nose or gums. Larger bruises (ecchymoses) may also develop. Neurological symptoms are present in up to 65% of patients, and may include headache, difficulty speaking, transient paralysis, numbness, fits, or coma, the last of which is a poor prognostic indicator. This is a result of clots temporarily interrupting local blood supply.〔 High blood pressure (hypertension) may be found on examination. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Thrombotic thrombocytopenic purpura」の詳細全文を読む スポンサード リンク
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