The thrombotic microangiopathies consist of a heterogeneous group of diseases which have common clinical manifestations including nonimmune hemolytic anemia, thrombocytopenia, and acute kidney injury. They also share in common endothelial cell injury and microthrombus formation as the central pathologic features (Fig. 1). While they share common clinical and pathologic manifestations, they have quite different and unique etiologies, presentations, pathogenesis, and therapies [1–6]. The most common cause of hemolytic uremic syndrome (HUS) is infectious agents with Shiga toxin-producing Escherichia coli (STEC) being the predominant cause of infectious HUS (Fig. 2). Atypical HUS (aHUS) can result from genetic mutations in complement regulatory proteins including complement factors H (FH), I (FI), and B (FB), as well as other factors. Thrombotic thrombocytopenia purpura (TTP) is caused by an inherited genetic mutation or an acquired immune deficiency in a disintegrin and metalloprotease with thrombospondin type 1 repeats 13 (ADAMTS13). ADAMTS13 cleaves von Willebrand factor (VWF) facilitating its release from endothelial cells, thereby preventing the accumulation of prothrombotic ultra-large VWF oligomers. Other less common causes of HUS include drug-induced HUS, cobalamin deficiency HUS, transplant-associated HUS, and other secondary causes of HUS such as systemic lupus erythematosus and malignant hypertension.
ASJC Scopus subject areas