Diagnosis of aHUS

Once routine biochemical and haematological analysis have demonstrated microangiopathic haemolytic anaemia, thrombocytopenia and acute renal failure, investigations are aimed at determining the underlying aetiology. There is no biomarker which will identify complement mediated aHUS at initial presentation and the diagnosis is one of exclusion. 

The most urgent test is an ADAMTS13 assay which is a prerequisite for Eculizumab initiation in adults. In children due to the rarity of TTP and the difficulty of plasma exchange Kidney Disease: Improving Global Outcomes (KDIGO) recommended that Eculizumab can be commenced prior to the ADAMTS13 result with the caveat that clinical deterioration on eculizumab should necessitate immediate plasma therapy. 

Other differential diagnosis of complement mediated aHUS must be sought (see below) however they are not required prior to initiation of Eculizumab.


The following diagnostic criteria for aHUS have been agreed by the aHUS Rare Disease Group: 


  • Renal biopsy showing a thrombotic microangiopathy 


  • Triad of microangiopathic haemolytic anaemia, thrombocytopenia and renal failure 


  • Thrombotic thrombocytopenic purpura 
  • Shiga toxin associated HUS 
  • Drug mediated TMA 
  • Infection (HIV, Streptococcus pneumonia) 
  • Transplantation (bone marrow, liver, lung, cardiac) 
  • Cobalamin deficiency 
  • Systemic lupus erythematosis 
  • Antiphospholipid antibody syndrome 
  • Scleroderma 

Emergency Referrals:  If you have a case of suspected aHUS and you would like your patient to be considered for treatment with eculizumab please follow our guidance for EMERGENCY REFERRALS. 

Find Out More

What is STEC-HUS?

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What is TTP?

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Secondary TMAs

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Genetics of aHUS

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