Hemolytic uremic syndrome

Background

• Similar to TTP (which is more common in adults), but associated with less central nervous system and more renal involvement.
• Most cases occur in children <10yr (⅔ of cases in < 5yr)
• Most cases due to E. coli O157:H7 infection
• Shiga toxin may induce autoantibody to CD36 (found on endothelial cells and platelets)
• May also be caused by shigella, yersinia, campylobacter, salmonella

Types

1. Typical
   • Occurs 2-14d after development of infectious diarrhea (bloody, no fever)
2. Atypical
   • Occurs in older children and adults
   • Extrarenal involvement is common (difficult to distinguish from TTP)
   • May be caused by atypical pathogens (EBV, S. pneumo) or immunosuppression

Clinical Features

Triad

1. Acute renal failure
2. Thrombocytopenia
3. Microangiopathic Hemolytic Anemia (MAHA)

Other Associated Conditions

1. Enteritis
2. N/V, diarrhea (usually bloody), +/- fever
3. Hyperglycemia
4. Pancreatic beta-cell dealth due to microthrombi within pancreas

Differential Diagnosis

1. Gastroenteritis
2. Appendicitis
3. Colitis
4. Intussusception
5. IBD
6. Perforation
7. DIC
8. TTP
9. SLE

Causes of Glomerulonephritis

• Poststreptococcal glomerulonephritis
• Hemolytic-uremic syndrome
• Henoch-Schonlein purpura
• IgA nephropathy
• Lupus nephritis
• Alport syndrome
• Goodpasture syndrome
• Paraneoplastic

Work-Up

• CBC
  • Checking for Schistocytes and Thrombocytopenia
• Stool tests
  • Shiga toxin, E. coli O157:H7 test
• UA
  • Hematuria, casts
• LFT
  • Increased bilirubin
• Chemistry
  • Creatinine, hyperkalemia (renal failure)

Treatment

1. Plasma exchange (plasmapheresis)
2. Transfusion of RBCs (only severe bleeding)
   • Generally only indicated if plasma exchange cannot be performed immediately
3. Platelet Transfusion is AVOIDED
   • Only used for life-threatening bleeding or intracranial hemorrhage under guidance from hematologist
   • Platelet infusion may lead to acutely worsened thrombosis, renal failure, and death
4. Hemodialysis
   • Often needed for renal failure and hyperkalemia treatment
5. AVOID Antibiotics
   • May lead to worsening lysis of bacteria and further toxin release
6. AVOID Antimotility agents
   • Leads to prolonged gut exposure to toxins

Disposition

• Admit

Source

• Corrigan J. Boineau FG. Hemolytic-uremic syndrome. Pediatr Rev. Nov 2001;22(11):365-9
• George J. Clinical practice. Thrombotic thrombocytopenic purpura. N Engl J Med 2006; 354:1927