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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