Untying the knot of thrombotic thrombocytopenic purpura and atypical hemolytic uremic syndrome.

Patients presenting with microangiopathic hemolysis and thrombocytopenia are often given the diagnosis of thrombotic thrombocytopenic purpura and treated with plasma exchange until the acute episode is over. Recent findings have shown that acquired thrombotic thrombocytopenic purpura is a chronic autoimmune disease with inhibitory antibodies of a disintegrin and metalloprotease with thrombospondin repeat, member 13 and are at risk of relapses that may be preventable. Furthermore, many of the patients given the diagnosis of thrombotic thrombocytopenic purpura really have atypical hemolytic uremic syndrome due to defective complement regulation that can be more effectively treated to prevent death and end-stage renal failure with eculizumab, a humanized monoclonal antibody of complement C5. These advances indicate that an accurate differential diagnosis of microangiopathic hemolysis is essential for optimal patient management.