Haemolytic Uraemic Syndrome



Haemolytic uraemic syndrome (HUS) occurs when there is thrombosis in small blood vessels throughout the body. This is usually triggered by a bacterial toxin called the shiga toxin. It leads to the classic triad of:

  • Haemolytic anaemia
  • Acute kidney injury
  • Low platelet count (thrombocytopenia)

 

The formation of blood clots consumes platelets, leading to thrombocytopenia. The blood clots within the small vessels chop up the red blood cells as they pass by (haemolysis), causing anaemia. The blood flow through the kidney is affected by the clots and damaged red blood cells, leading to acute kidney injury.

The most common cause is a toxin produced by the bacteria e. coli 0157 called the shiga toxin. Shigella also produces this toxin and can cause HUS. The use of antibiotics and anti-motility medications such as loperamide to treat the gastroenteritis increase the risk of developing HUS.

Presentation

E. coli 0157 causes a brief gastroenteritis often with bloody diarrhoea.

Around 5 days after the diarrhoea the person will start displaying symptoms of HUS:

  • Reduced urine output
  • Haematuria or dark brown urine
  • Abdominal pain
  • Lethargy and irritability
  • Confusion
  • Hypertension
  • Bruising

Management

HUS is a medical emergency and has up to 10% mortality. The condition is self limiting and supportive management is the mainstay of treatment:

  • Antihypertensives
  • Blood transfusions
  • Dialysis

 

70-80% of patients make a full recovery.

 

Last updated April 2019
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