<prompt> About HUS all are true except :Not commonly caused by verocytogenic E coliCauses mild to severe Coombs positive hemolytic anemiaRecurrences rareTransient thrombocytopenia  <response>: Causes mild to severe Coombs positive hemolytic anemia Hemolytic-uremic syndrome H.U.S. is the most common cause of acute renal failure in young children. It is classically characterized by the triad of - Microangiopathic hemolytic anemia - Thrombocytopenia - Uremia Etiology Hemolytic uremic syndrome is preceeded by bacterial infections The bacterias commonly associated are : E.coli Verocytogenic E.coli is the most common ause of hemolytic uremic syndrome in Nelson states An acute enteritis with diarrhoae caused by shiga-like toxin producing escherichia coli verocytogenic E. coli 0157:117 precedes 80 or more of HUS cases in developed countries An impoant point Some say that option a was - Not commonly caused by verocytogenic E.coli in Asia If this was the option then it is a true statement. - The infection associated with H. U.S. varies with region In developed countires Noh America and Europe - Verocytogenic E coli or Shiga like toxin producing Eschererichia coli is the most common cause 80 of all the cases. In Asia India - Shigella dysenteriae is the chief pathogen. The anemia associated with hemolytic uremic syndrome is coombs negative hemolytic anemia. Coombs positive hemolytic anemia occurs when the anemia is caused due to autoantibodies produced in the body. In H.U.S. the hemolytic anemia is caused by mechanical damage to R.B.C. when they pass through nucrothrombi which are formed in capillaries due to platelet aggregation. The red cells while passing through these capillaries get attached to the thrombus and gets fragmented causing hemolysis, Autoantibodies have nothing to do with hemolytic uremic syndrome. So the anemia will not be coombs positive. Thrombocytopenia in H.U.S. A low platelet count can usually but not always be detected early in the illness, but it may then become normal or even high. If a platelet count obtained within 7 days after onset of the acute gastrointestinal illness is not 150,000mm3, other diagnosis should be considered. Recurrence in H.U.S. Recurrence is rare in H.U.S. There may be disease recurrence only in familial or non diarrhoea associated cases. 