[Treatment of thrombotic microangiopathies].

Thrombotic thrombocytopenic purpura and hemolytic uremic syndrome appear as the same expression of thrombotic microangiopathy (TMA), which is a single pathological entity affecting small blood vessels leading to hemolytic anemia, circulatory changes with renal (hemolytic uremic syndrome, HUS) or nervous (thrombotic thrombocytopenic purpura, TTP) involvement. Because of his low incidence, prospective randomized clinical trials are difficult to conduct and apart from plasma exchanges (PE) which appear superior to plasma infusions (PI), other therapeutic recommendations are based on retrospective studies or on anecdotal reports with limited number of patients. In the absence of appropriate therapy, mortality rate was initially above 90% in adults with TTP. Plasma infusions and plasma exchanges have dramatically improved prognosis of the disease, since more than 80% of patients respond to therapy with a survival greater than 80 to 90%. Analysis of data of medical literature shows that plasma exchanges can cure 82% of TMA with 15% of refractory TMA and a mortality rate of 14%. In two randomized trials, PE are more effective than PI with a response rate benefit of 25% and an overall survival increase of 15%. Although severe thrombocytopenia is frequently observed, it is important to avoid platelet transfusions. Platelets infusions induce deleterious effects since they add to the severity and the extend of microvascular thrombi formation. Use of glucocorticoids, heparin, antiplatelet therapy, intravenous immunoglobulin and vincristine are associated with variable results and no controlled study supports their use. Splenectomy is still under discussion but could be of interest in case of relapsing thrombotic microangiopathies as an attempt to reduce the rate of TMA recurrence.