Como resultado, la actividad de la enzima que falta o se cambia. Alrededor de 1. Muchas personas que han heredado TTP han llamaradas frecuentes que necesitan ser tratados. Estos tratamientos han mejorado enormemente las perspectivas de la enfermedad. Como resultado, la actividad de la enzima que falta o se altera. En heredado PTT, una persona nace con dos copias del gen alterado, uno de cada padre.
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Probable etiology may involve, at least in some cases, endothelial damage,  although the formation of thrombi resulting in vessel occlusion may not be essential in the pathogenesis of secondary TTP. Mechanism[ edit ] The underlying mechanism typically involves autoantibody-mediated 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 increases platelet adhesion to areas of endothelial injury, particularly where arterioles and capillaries meet, which in turn results in the formation of small platelet clots called thrombi. As platelets are used up in the formation of thrombi, this then leads to a decrease in the number of overall circulating platelets, which may then cause life-threatening bleeds. 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.
The presence of these blood clots in the small blood vessels reduces blood flow to organs resulting in cellular injury and end organ damage. Differential diagnosis[ edit ] TTP is characterized by thrombotic microangiopathy TMA , the formation of blood clots in small blood vessels throughout the body, which can lead to microangiopathic hemolytic anemia and thrombocytopenia. This characteristic is shared by two related syndromes, hemolytic-uremic syndrome HUS and atypical hemolytic uremic syndrome aHUS.
In addition to TMA, one or more of the following symptoms may be present in each of these diseases: neurological symptoms e. Transfusion is contraindicated in thrombotic TTP, as it fuels the coagulopathy. Since the early s, plasmapheresis has become the treatment of choice for TTP. If apheresis is not available, fresh frozen plasma can be infused, but the volume that can be given safely is limited due to the danger of fluid overload.
People with refractory or relapsing TTP may receive additional immunosuppressive therapy, e. Some tolerate longer intervals between plasma infusions. Additional plasma infusions may be necessary for triggering events, such as surgery; alternatively, the platelet count may be monitored closely around these events with plasma being administered if the count drops. Moschcowitz ascribed the disease incorrectly, as now known to a toxic cause.
Moschcowitz noted his patient, a year-old girl, had anemia, small and large bruises, microscopic hematuria , and, at autopsy, disseminated microvascular thrombi.
The identification of a deficient protease in people with TTP was made in s.
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