Aetiology
Typical HUS is most commonly caused by infections:
- Most common: Shiga toxin-producing E. coli (E. coli O157)
- Streptococcus pneumoniae
- Influenza virus
Atypical HUS (rare) arises from primary defects in complement regulation, independent of infection.
Clinical Manifestation
Classic triad of:
- MAHAMicroangiopathic haemolytic anaemia
- Thrombocytopaenia
- AKIAcute kidney injury
Investigation and Diagnosis
| Investigation | Finding in HUS |
|---|---|
| FBC | Features of MAHAMicroangiopathic haemolytic anaemia
Thrombocytopaenia |
| Blood film | Schistocytes (from MAHAMicroangiopathic haemolytic anaemia) |
| Renal profile | ↑ Creatinine (AKIAcute kidney injury) |
| Coagulation screen | Normal in HUS (helps exclude DICDisseminated intravascular coagulation) |
| ADAMTS13 activity | Normal activity (severe deficiency suggests TTPThrombotic thrombocytopaenic purpura) |
| Stools sample | Presence of Shiga toxin (confirms typical HUS) |
Management
The mainstay of management of typical HUS is supportive care (IV fluids, correct electrolyte changes, dialysis if required)
- Antibiotics should generally be avoided (may worsen toxin release)
- Plasma exchange and immunosuppressants are NOT routinely indicated in typical HUS
In contrast, atypical HUS is managed with complement inhibitors (e.g. eculizumab, ravulizumab)