haemolytic uraemic syndrome

Last edited 08/2021 and last reviewed 08/2021

Haemolytic uraemic syndrome is the triad of:

  • acute renal failure (acute kidney injury)
  • microangiopathic haemolytic anaemia
  • thrombocytopenia

The thrombocytopenia is thought to be a consequence of platelet consumption at sites of endothelial injury. Despite this blood clotting times (prothrombin time, kaolin clotting time) are normal.

It is now believed that thrombotic thrombocytopenic purpura and haemolytic uraemic syndrome represent a spectrum of disease.

The term HUS encompasses several different disease processes which can be broadly divided into infection-induced HUS, HUS secondary to a pre-existing condition, or atypical HUS (aHUS)

  • about 90% of cases of HUS are considered infection-induced andare most typically associated with either Shiga toxin-producingEscherichia coli (STEC) or Streptococcus pneumoniae
    • STEC-associated cases are often (but not always) preceded by the onset of bloody diarrhoea
  • pre-existing conditions associated with development of HUS include:
    • autoimmune diseases for example, systemic lupus erythematosus, scleroderma
    • stem cell or solid organ transplantation,
    • drugs for example, quinine, mitomycin, cyclosporin
    • pregnancy

Atypical hemolytic uremic syndrome (aHUS) is a rare, complement-mediated disease associated with poor outcomes if untreated

  • the endothelial damage caused by thrombotic microangiopathy (TMA) can result in life-threatening manifestations of the disease, including kidney failure and extrarenal tissue damage
  • prior to the availability of targeted treatment with complement C5 inhibitors, the prognosis of aHUS both in pediatric and adult patients was poor- around 29% of children required dialysis or died within 1 year and 48% reached chronic kidney disease (CKD) stage 5 or death at 3 years despite plasma therapy


  • Loirat C, Fakhouri F, Ariceta G, Besbas N, Bitzan M, Bjerre A, et al. An international consensus approach to the management of atypical hemolytic uremic syndrome in children. Pediatric Nephrology 2016;31(1):15-39
  • Fakhouri F, Zuber J, Fremeaux-Bacchi V, Loirat C. Haemolytic uraemic syndrome. Lancet 2017;390(10095):681-96.
  • Tanaka K, Adams B, Aris AM, Fujita N, Ogawa M, Ortiz S, Vallee M, Greenbaum LA. The long-acting C5 inhibitor, ravulizumab, is efficacious and safe in pediatric patients with atypical hemolytic uremic syndrome previously treated with eculizumab. Pediatr Nephrol. 2021 Apr;36(4):889-898