Renal Thrombotic Microangiopathy: A Review

Thrombotic microangiopathy (TMA) is a pathological lesion observed in a wide spectrum of diseases, triggered by endothelial injury and/or dysfunction. Although TMA lesions are often accompanied by clinical features of microangiopathic hemolytic anemia, thrombocytopenia and ischemic end organ injury, renal-limited forms of TMA are not infrequently encountered in clinical practice. The presence of renal-limited manifestations can be diagnostically challenging, often delaying initiation of targeted therapy. Prompt investigation and empiric treatment of TMA is warranted to reduce associated morbidity and mortality. Major advances have been made with respect to the pathophysiology of primary TMA entities, with the subsequent development of novel diagnostic tools and lifesaving therapies for diseases like thrombotic thrombocytopenic purpura and complement-mediated TMA. This article will review the clinical presentation and pathologic hallmarks of TMA involving the kidney, and the disease-specific mechanisms that contribute to the endothelial injury that characterizes TMA lesions. Diagnostic approach, and both empiric and disease-specific treatment strategies will be discussed, along with the potential role for emerging targeted disease-specific therapies.