Hemolytic-uremic syndrome

Hemolytic-uremic syndrome 

Updated: 07/25/2023

© Jun Wang, MD, PhD

General features
  • Most common cause of acute kidney injury in children
  • Associated with Shiga-like toxin
  • More common in summer
  • Need to differentiated from TTP
Clinical presentations
  • Usually with history of bloody diarrhea
  • Progressive renal failure
  • Microangiopathic (nonimmune, Coombs-negative) hemolytic anemia
  • Thrombocytopenia
  • Neurological presentation less common
Key risk factors
  • Bacterial infection, most commonly due to E coli (O157:H7 most common), S dysenteriae, Salmonella typhi, etc
“Atypical” HUS
  • Similar clinical presentation but NOT associated with Shiga-like toxin
  • Commonly in adults
  • May occur in any season
  • Usually NO history of bleeding diarrhea
  • Probably genetic defects in complement factor H, membrane cofactor protein (CD46), or factor I
  • Excessive activation of complement pathway
  • Poor prognosis, rapid progress to renal failure
Key pathogenesis
  • Endothelial injury caused by Shiga-like toxin or excessive activation of complement pathway
Key Laboratory findings
  • Acute renal failure: Elevated BUN, creatinine
  • Thrombocytopenia
  • Hemolytic anemia
  • Hemolysis
  • Usually normal PT, aPTT, D-dimers (different from coagulative disorders, DIC)
  • Stool culture of E coli O127:H7 or Shigella bacteria
  • ADAMTS13 may be reduced, but not as severe as thrombotic thrombocytopenic purpura
Key morphological features
  • Schistocytosis
  • Hyalinelike thrombi usually in small vessels of kidney only
HUS vs TTP


Management
  • Supportive: Red cell transfusion, platelet transfusion if significantly bleeding, fluid, etc
  • Plasma exchange fro atypical HUS

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