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 ane mia, circulatory changes with renal (hemolytic uremic syndrome, HUS) or ner vous (thrombotic thrombocytopenic purpura, TTP) involvement. Because of his low incidence, prospective randomized clinical trials are difficult to con duct and apart from plasma exchanges (PE) which appear superior to plasma i nfusions (PI), other therapeutic recommendations are based on retrospective studies or on anecdotal reports with limited number of patients. In the ab sence of appropriate therapy, mortality rate was initially above 90% in adu lts with TTP. Plasma infusions and plasma exchanges have dramatically impro ved prognosis of the disease, since more than 80% of patients respond to th erapy with a survival greater than 80 to 90%, Analysis of data of medical l iterature shows that plasma exchanges can cure 82% of TMA with 15% of refra ctory TMA and a mortality rate of 14%. In two randomized trials, PE are mor e effective than PI with a response rate benefit of 25% and an overall surv ival increase of 15%. Although severe thrombocytopenia is frequently observ ed, it is important to avoid platelet transfusions, Platelets infusions ind uce deleterious effects since they add to the severity and the extend of mi crovascular thrombi formation. Use of glucocorticoids, heparin, antiplatele t therapy, intravenous immunoglobulin and vincristine are associated with v ariable results and no controlled study supports their use, Splenectomy is still under discussion but could be of interest in case of relapsing thromb otic microangiopathies as an attempt to reduce the rate of TMA recurrence.