Thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS): The new thinking

TTP and HUS are two disorders with many similarities. Though their first descriptions appeared at different time in history, there has been a trend among physicians to consider them as the same clinical entity. However, in recent years new research findings on the pathophysiology of TTP and HUS have revealed some differences between the two disorders. In this paper, we will review the current approaches to the clinical and laboratory diagnosis of TTP and HUS, as well as therapeutic strategies. We will also summarize the recent advances in three areas in the study of the pathophysiology of TTP and HUS, namely the newly discovered von Willebrand factor multimer-cleaving protease, endothelial cell apoptosis induced by serum from patients with TTP and atypical HUS and the activation of complement system. Since distinguishing and differentiating between TTP and HUS may help to develop more effective therapies targeted at key steps of the disease development, we will discuss possible ways of reclassifying the TTP-HUS disorders. In the end, we also present our views on possible future development.