Paeds · nephrology-urology-fluids-and-electrolytes
Haemolytic uraemic syndrome
Also known as HUS · STEC-HUS · Typical haemolytic uraemic syndrome · Atypical haemolytic uraemic syndrome · aHUS
Fellowship guide to paediatric haemolytic uraemic syndrome: the defining triad of microangiopathic haemolytic anaemia, thrombocytopenia, and acute kidney injury; the distinction between STEC-HUS (approximately 90 percent of cases, following Shiga toxin-producing E. coli) and atypical HUS from complement dysregulation; the critical point that supportive care is the mainstay for STEC-HUS while eculizumab is first-line for aHUS; and the need for long-term renal follow-up in all survivors.
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Target exams
Red flags
- A child under five with pallor, oliguria or anuria, and a recent history of bloody diarrhoea
- Microangiopathic haemolytic anaemia with schistocytes and thrombocytopenia with acute kidney injury
- Diarrhoea-negative thrombotic microangiopathy suggesting atypical HUS requiring urgent complement blockade
- Neurological involvement including seizures, altered consciousness, or stroke in HUS indicating severe disease
- Rising creatinine with refractory hyperkalaemia, metabolic acidosis, or fluid overload requiring dialysis
- Severe hypertension or hypertensive encephalopathy from renin-mediated vasoconstriction
- Recurrent HUS or family history suggesting complement-mediated aHUS requiring lifelong management
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- Recognises the triad of haemolytic uraemic syndrome and distinguishes typical STEC-HUS from atypical HUS
- Initiates supportive care including careful fluid management and transfusion thresholds
- Refers urgently to paediatric nephrology and intensive care
- Justifies the use of eculizumab in atypical HUS and explains the complement pathway basis
- Distinguishes HUS from TTP using ADAMTS13 and from DIC using coagulation studies
- Manages long-term renal sequelae and the decision around eculizumab in aHUS and post-transplant recurrence
- Definition and triad of haemolytic uraemic syndrome
- Classification into STEC-HUS, atypical HUS, and secondary HUS
- Principles of supportive care and when to involve nephrology
- Recognises a deteriorating child with HUS and escalates appropriately
- Communicates the diagnosis, prognosis, and need for long-term follow-up to families
- Counsels on aHUS, genetic testing, and complement blockade therapy
- Level 1: Recognition of the HUS triad and association with E. coli gastroenteritis
- Level 2: Initiation of supportive care and differentiation of STEC-HUS from aHUS
- Level 3: Management of eculizumab therapy and coordination of long-term renal follow-up
- HUS triad and the role of Shiga toxin-producing E. coli O157:H7
- Distinction between STEC-HUS, atypical HUS, and secondary HUS
- Role of eculizumab in atypical HUS and the basis of complement dysregulation
- Assessment and initial management of a child with pallor, oliguria, and a history of bloody diarrhoea
- Interpretation of blood film showing schistocytes with normal coagulation
- Structured explanation of supportive care and the rationale for eculizumab in aHUS
- Recognition and supportive management of haemolytic uraemic syndrome
- Classification into STEC-HUS and atypical HUS and the role of complement genetics
- Eculizumab therapy for aHUS and the avoidance of antibiotics and antimotility agents in STEC infection
- Recognition of HUS as a cause of acute kidney injury in young children
- Initiation of supportive care and urgent nephrology referral
- Family communication on diagnosis, prognosis, and long-term follow-up
- Canadian approach to HUS classification and management
- Eculizumab use in atypical HUS and post-transplant prophylaxis
- Long-term renal surveillance after HUS recovery
Overview & Definition
A previously well toddler who had bloody diarrhoea a week ago and now arrives pale, listless, and passing very little urine has haemolytic uraemic syndrome. The name describes the three things going wrong at once: red blood cells are being destroyed inside narrowed blood vessels (haemolytic anaemia), platelets are being consumed as clots form in those vessels (thrombocytopenia), and the vessels that are most affected are in the kidneys, where the clots block the filtering surface and shut down urine production (uraemia). This triad, caused by widespread thrombotic microangiopathy in small vessels, defines the syndrome regardless of the trigger. [1]
The trigger is usually an intestinal infection. About 90 percent of paediatric HUS follows gastroenteritis caused by Shiga toxin-producing Escherichia coli, most commonly the O157:H7 strain, and this form is called typical or STEC-HUS. A much smaller but far more dangerous group, accounting for 5 to 10 percent of cases, has no diarrhoeal prodrome and is driven by uncontrolled activation of the body's complement immune pathway. This is atypical HUS, and the distinction between the two is the single most consequential decision in the disease because atypical HUS requires urgent treatment with eculizumab, a complement-blocking drug, while typical STEC-HUS is managed with supportive care alone. [3]
References12ShowHide
- [1]Tarr PI, Gordon CA, Chandler WL Shiga-toxin-producing Escherichia coli and haemolytic uraemic syndrome. Lancet, 2005.PMID 15781103
- [2]Noris M, Remuzzi G Atypical hemolytic-uremic syndrome. N Engl J Med, 2009.PMID 19846853
- [3]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. Pediatr Nephrol, 2016.PMID 25859752
- [4]Keir LS, Saleem MA Current evidence for the role of complement in the pathogenesis of Shiga toxin haemolytic uraemic syndrome. Pediatr Nephrol, 2014.PMID 23843163
- [5]Rosales A, Hofer J, Zimmerhackl LB, Jungraithmayr TC, Riedl M, Giner T, et al Need for long-term follow-up in enterohemorrhagic Escherichia coli-associated hemolytic uremic syndrome due to late-emerging sequelae. Clin Infect Dis, 2012.PMID 22412065
- [6]Schaefer F, Ardissino G, Ariceta G, Fakhouri F, Scully M, Isbel N, et al Clinical and genetic predictors of atypical hemolytic uremic syndrome phenotype and outcome. Kidney Int, 2018.PMID 29907460
- [7]Le Clech A, Simon-Tillaux N, Provôt F, et al. Atypical and secondary hemolytic uremic syndromes have a distinct presentation and no common genetic risk factors. Kidney Int, 2019.PMID 30982675
- [8]Lapeyraque AL, Malina M, Fremeaux-Bacchi V, Boppel T, Kirschfink M, Oualha M, et al Eculizumab in severe Shiga-toxin-associated HUS. N Engl J Med, 2011.PMID 21612462
- [9]Percheron L, Gramada R, Tellier S, et al. Eculizumab treatment in severe pediatric STEC-HUS: a multicenter retrospective study. Pediatr Nephrol, 2018.PMID 29572749
- [10]de Zwart PL, Mueller TF, Spartà G, Luyckx VA Eculizumab in Shiga toxin-producing Escherichia coli hemolytic uremic syndrome: a systematic review. Pediatr Nephrol, 2024.PMID 38057431
- [11]Frank C, Werber D, Cramer JP, Askar M, Faber M, an der Heiden M, et al Epidemic profile of Shiga-toxin-producing Escherichia coli O104:H4 outbreak in Germany. N Engl J Med, 2011.PMID 21696328
- [12]Bresin E, Rurali E, Caprioli J, Sanchez-Corral P, Fremeaux-Bacchi V, Rodriguez de Cordoba S, et al Combined complement gene mutations in atypical hemolytic uremic syndrome influence clinical phenotype. J Am Soc Nephrol, 2013.PMID 23431077