Hemolytic-uremic syndrome

Background

• Typical HUS is a thrombotic microangiopathy with prominent renal failure traditionally associated with Shiga toxin-producing Escherichia coli infection, especially enterohemorrhagic E. coli O157:H7
• Different pathophysiology and treatment from atypical hemolytic-uremic syndrome and secondary hemolytic-uremic syndrome

Pathophysiology

• Typical HUS is caused by Shiga toxin from enterohemorrhagic Escherichia coli (e.g. O157:H7)
• Shiga toxin is absorbed systemically
  • Damages vascular endothelial cells leading to cytokine release and thrombus formation
  • Actives complement and binds Factor H (a complement regulator)

Risk Factors

• Younger age
• Exposure to antibiotics
• Increased WBC count
• Vomiting
• Prolonged diarrhea
• Presence of stx2a and eae genes

Clinical Manifestations

• Abdominal pain and watery diarrhea about 4 days after exposure to toxin, progressing to bloody diarrhea with or without vomiting
  • Up to one third do not have bloody diarrhea
  • Fever is mild or absent
• About 7 days after onset of diarrhea, HUS develops
  • Progression of hemolytic anemia, thrombocytopenia, and severe AKI
• Other preceding infections can include UTI, SSTI, or other causes of gastroenteritis

Management

• Supportive