Hemolytic-uremic syndrome

Hemolytic-uremic syndrome (HUS), is essentially a vasculopathy characterized by hemolytic anemia, acute renal failure and thrombocytopenia. It is caused by a variety of agents but most commonly by E. coli O157:H7, which is a gram negative bacteria acquired via contaminated food or drinks.

Pathophysiology:
-Shiga toxin-producing E. coli (STEC) or enterohemorrhagic E. coli (EHEC) produce a toxin called verotoxin or shiga-like toxin.
-Toxin enters the bloodstream and causes damage to the body's vascular endothelium.
-Endothelial damage leads to platelet activation that causes thrombocytopenia. The renal glomerular endothelial cells express a receptor for the toxin.

Clinical features:
-HUS is characterized by the triad of hemolytic anemia, thrombocytopenia, and acute renal failure.
-Preceding bloody diarrhea may or may not be present.
(HUS must be distinguished from Thrombotic thrombocytopenic purpura (TTP) which in addition to the triad above has fever and neurological signs. TTP is caused by an acquired defect in the protein ADAMTS13.)

Treatment:
-Supportive treatment for low platelets (transfusion if bleeding)
-Supportive treatment of renal failure (electrolyte balance, dialysis as needed)
-Plasmapheresis is often used in early cases to get rid of the circulating toxin
-With supportive care majority of the patients have good renal outcomes