Hemolytic uremic syndrome (HUS) is characterized by a triad of hemolytic anemia, thrombocytopenia and acute renal failure. The underlying lesion is thrombotic microangiopathy, which includes endothelial swelling with fibrin deposition that predominates in the renal microvasculature, but extrarenal manifestation can also occur.
There are two forms of HUS: typical and atypical. Typical HUS is often preceded by diarrhea, the most common pathogens are Shiga-toxin producing Escherichia coli (STEC) serotype O157:H7, Shigella dysenteria and Shigella flexneri. Atypical form (aHUS) is caused by the dysregulated activation of the complement cascade. This can be caused by mutations in the genes encoding regulatory proteins factor H, membrane cofactor protein etc, as well as by mutations in the genes encoding C3 convertase proteins.
In the treatment of typical HUS, the emphasis should be on supporting the kidney function and in aHUS on plasma therapy and administration of eculizumab.