RESUMEN
Hemolytic uremic syndrome (HUS) is a type of thrombotic microangiopathy where organic damage predominates in the kidney. Atypical HUS (aHUS) is a rare disease that affects young adults and causes terminal chronic renal failure ending in dialysis, in most cases. It also recurs after kidney transplantation. aHUS is associated with genetic defects of the alternative complement pathway or its activation by other factors such as drugs, autoimmune diseases, infections, malignant hypertension and ischemia-reperfusion. We report two women aged 17 and 25 years old with catastrophic aHUS. In both cases, complement amplifying factors (drugs and infections) were added and acted on a genetic vulnerability to precipitate complement activation and produce aHUS. Both patients developed terminal renal failure and had to undergo hemodialysis. Fortunately, after a broad etiological study, it was possible to make the diagnosis of aHUS and start treatment with Eculizumab, a monoclonal antibody that changed the natural history of aHUS. It inhibits complement activity controlling microangiopathy and preventing the development of end-stage renal disease. It also improves the success rate in kidney transplantation. In the case of our patients, both discontinued dialysis after chronic treatment with Eculizumab.