Background

  • Clinical triad of thrombocytopenia, microangiopathic hemolytic uremia, and acute kidney injury
  • Most common in children between ages 3 and 5
  • Typically occurs after diarrheal illness caused by Shiga toxin-producing coli (STEC; >90% of cases) or Shigella dysenteriae type 1 infection. However, it can be observed after infection with S. pneumoniae or in connection with is dysregulation of the alternative complement cascade
  • Characterized by prothombotic and proinflammatory state on the endothelial surface

Clinical Manifestations

  • Patients commonly have a history of gastroenteritis symptoms, including watery diarrhea that subsequently becomes bloody
  • HUS usually occurs 1 week after diarrhea, with oligoanuric acute kidney injury
    • Other symptoms include hypertension (owing to fluid retention and edema) and manifestations of thrombocytopenia and anemia
  • Extrarenal manifestations:
    • Neurologic: including encephalopathy, seizures, coma
    • Cardiovascular: ischemia, cardiac failure
    • Endocrine: diabetes
    • Gastrointestinal: pancreatitis, cholecystitis, necrosis, perforation, stricture formation

Laboratory Studies

  • Laboratory studies should include CBC (anemia, thrombocytopenia), smear (schistocytes), BMP (elevated BUN/creatinine), LDH (elevated), haptoglobin (low), and urinalysis (hematuria, RBC casts, proteinuria)
  • Troponin and pancreatic enzymes may be elevated

Differential Diagnosis

  • Differential diagnosis includes TTP, DIC, post-infectious glomerulonephritis, lupus, HSP, and sepsis

Management 

  • Most patients are managed with supportive care, with close attention to fluid and electrolytes
  • Some patients may require pRBC and/or platelet transfusions for severe anemia or thrombocytopenia, loop diuretics for fluid overload, and dialysis or CRRT for anuria
  • Adequate nutrition is important
  • There is conflicting evidence concerning whether the use of antibiotics in patients with STEC infection can precipitate HUS; such use is generally not recommended
  • Antimotility agents are contraindicated in children with HUS because of the risk of developing toxic megacolon

Disposition

  • Patients with HUS should be admitted, either to the floor or the PICU, depending on hemodynamic status and need for interventions such as CRRT

Prognosis

  • Mortality rates are up to 10%, and up to 40% of children may develop long-term complications such as hypertension, proteinuria, and renal complications (including ESRD).

References

American Academy of Pediatrics. Hemolytic-Uremic Syndrome. In: McInerny TK, Adam HM, Campbell DE, DeWitt TG, Foy JM, Kamat DM, eds. American Academy of Pediatrics Textbook of Pediatric Care, 2nd Edition. American Academy of Pediatrics; 2017.

Cody, EM; Dixon, BP (February 2019). “Hemolytic Uremic Syndrome”. Pediatric Clinics of North America. 66 (1): 235–246.

Freedman, Stephen & Xie, Jianling & Neufeld, Madisen & Hamilton, William & Hartling, Lisa & Tarr, Phillip. (2016). Shiga Toxin-Producing Escherichia coli Infection, Antibiotics, and Risk of Developing Hemolytic Uremic Syndrome: A Meta-Analysis. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 62. 10.1093/cid/ciw099.

Walsh PR, Johnson S. Treatment and management of children with haemolytic uraemic syndrome. Archives of Disease in Childhood 2018;103:285-291.