Snapshot A 7-year-old boy recently had several episodes of bloody diarrhea. Desperate, his parents called his primary care physician, who reassured them that the infection is self-limited. Still concerned, his parents bought some diarrhea pills (anti-motility agents). A week later, he presents to the ER with jaundice, abdominal pain, and easy bruising. Lab results come back with low platelet count, anemia, and increased creatinine. A peripheral blood shows schistocytes. He is started on IV hydration. Introduction Syndrome commonly seen in children most commonly caused by Escherichia coli O157:H7 (EHEC) acute diarrhea due to Shiga-like toxin S. pneumoniae infection Shigella spp. Shiga toxin Classic triad thrombocytopenia (first) nonimmune microangiopathic hemolytic anemia (second) acute renal failure (hence, “uremia” in title) (third) Similar to TTP but without fever and neurologic symptoms Epidemiology Most commonly in children Exposed to E. coli raw or undercooked meat unwashed fruits/vegetables animals at petting zoos Risk factors use of antimotility agents in EHEC diarrhea use of antibiotics in EHEC diarrhea ETIOLOGY Pathogenesis toxin damages endothelium microthrombi form at site of damage consumes platelets → thrombocytopenia intravascular mechanical hemolysis → schistocytes decreases renal blood flow → acute renal failure Presentation Symptoms prodromal gastrointestinal illness abdominal pain bloody diarrhea nausea vomiting fatigue (anemia) oliguria/anuria (renal failure) Physical exam pallor (anemia) jaundice (hemolysis) petechiae/purpura uncommon hepatosplenomegaly STUDIES Criteria for HUS hemolytic anemia hematocrit < 30% schistocytes (helmet cells) on peripheral smear thrombocytopenia ↑ serum creatinine Normal PT/PTT Negative Coombs test ↑ bleeding time Differential Characteristics DIC ITP TTP HUS Fever No No Yes Yes/No Splenomegaly No No Yes Yes Platelets Low Low Low Low Bleeding time ↑ ↑ ↑ ↑ PT ↑ PTT ↑ Shistocytes Yes No Yes Yes Trauma Yes No No No Treatment Prevention prevent EHEC infection avoid raw or undercooked meat avoid antimotility agents or antibiotics Supportive care with fluids to maintain renal perfusion dialysis if acute renal failure unresponsive to fluids Fresh frozen plasma can be used (increases coagulation factor levels) Plasmapheresis or plasma exchange for severe cases Complications Chronic kidney disease Hypertension Heart failure Electrolyte abnormalities Prognosis 3-5% mortality 5% severe sequelae such as end-stage renal failure