haemolytic uraemic syndrome (HUS)

see also:

• thrombotic thrombocytopenic purpura (TTP)

• 1st defined as a syndrome in 1955
• causes a similar clinical condition to thrombotic thrombocytopenic purpura (TTP) but with:
  • being more common in children
  • less neurologic abnormalities
  • more renal impairments
  • ADAMTS13 levels above 5%
  • positive test for shiga-toxin/enterohemorrhagic E. coli (EHEC) (if this is negative then it is termed atypical HUS)

• 1.5 per 100,000 people are affected per year

• usually have initial bloody diarrhoea due to a shiga toxin E.coli gastroenteritis after eating contaminated food, the first symptoms of infection can emerge anywhere from 1 to 10 days later, but usually after 3 to 4 days
  • most common form of transmission is ingestion of undercooked meat, unpasteurized fruits and juices, contaminated produce, contact with unchlorinated water, and person-to-person transmission in daycare or long-term care facilities
  • mini-epidemics occasionally occur from the sale of contaminated foods
• HUS typically develops about 5–10 days after the first symptoms, but can take up to 3 weeks to manifest, and occurs at a time when the diarrhea is improving
• fever
• anaemia with schistocytes
• thrombocytopenia
• acute kidney injury (AKI) / acute renal failure (ARF)
• neurologic symptoms
• thrombotic microangiopathy (TMA) / microangiopathic hemolytic anemias (MAHAs)
• mortality < 5%
• 25% of survivors have chronic renal failure

• most cases occur after infectious diarrhea due to a specific type of Shiga-toxin producing E. coli called O157:H7 (STEC)
  • the binding action of Shiga-toxin also inactivates a metalloproteinase called ADAMTS13, the deficiency of which causes the closely related TTP.
• some are due to either:
  • S. pneumoniae
  • Shigella
  • Salmonella
  • certain medications
• Unlike typical HUS, atypical HUS does not follow STEC infection and is thought to result from one or several genetic mutations that cause chronic, uncontrolled, and excessive activation of complement

• supportive care
• may include dialysis, steroids, blood transfusions, or plasmapheresis.