Signs and symptoms
The classic case of HUS occurs after bloody diarrhea caused by E. coli O157:H7, a strain of E. coli that expresses verotoxin (also called Shiga toxin). The toxin enters the bloodstream, attaches to renal endothelium and initiates an inflammatory reaction leading to acute renal failure (ARF) and diffuse intravascular coagulation (DIC). The fibrin mesh destroys red blood cells and captures thrombocytes, leading to a decrease of both on full blood count. HUS occurs after 2-7% of all E. coli O157:H7 infections.
Clinically, HUS can be very hard to distinguish from Thrombotic Thrombocytopenic Purpura (TTP). The laboratory features are almost identical, and not every case of HUS is preceded by diarrhea. The only distinguishing feature is that in TTP, neurological symptoms occur more often, but this is not always the case.
Treatment is with dialysis and blood and platelet transfusion. Mortality of HUS is 3-5%. Often, plasmapheresis is also initiated, when there is diagnostic uncertainty between HUS and TTP.
About one-third of persons with hemolytic-uremic syndrome have abnormal kidney function many years later, and a few require long-term dialysis. Another 8% of persons with hemolytic uremic syndrome have other lifelong complications, such as high blood pressure, seizures, blindness, paralysis, and the effects of having part of their bowel removed.