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Haemolytic uraemic syndrome (HUS)
HUS is a triad of microangiopathic haemolytic anaemia, a low platelet count and acute kidney injury; in children it usually appears about a week after bloody diarrhoea from STEC, and treatment is supportive.
Why it matters in the exam
The typical case: a toddler who had bloody diarrhoea, improved, and about a week later becomes pale, passes little urine and is found to have low haemoglobin, low platelets, a high creatinine and schistocytes on the smear. Candidates are asked for the diagnosis, the cause (E. coli O157:H7 and other STEC), and what not to do — antibiotics and antimotility drugs in STEC diarrhoea, and platelet transfusion without bleeding.
The other forms should be known too: atypical HUS (no diarrhoea, recurrent, family history) results from defective complement regulation and is treated with eculizumab; and pneumococcal HUS, in which the direct Coombs test is positive and plasma should be avoided. The difference from TTP lies mainly in the ADAMTS13 level, which is very low in TTP.
The laboratory points the way: falling haemoglobin, high LDH, low haptoglobin, a negative direct Coombs (in typical HUS), low platelets and near-normal clotting tests — unlike DIC. The urine sometimes shows blood and protein. Most children with typical HUS recover, but a third to a half need temporary dialysis, and some are left with proteinuria, hypertension or reduced kidney function, so long follow-up is needed. Complications outside the kidney include brain involvement with seizures, pancreatitis and bowel injury. The main prevention is hygiene and cooking minced meat thoroughly.
Key points
- HUS: microangiopathic haemolytic anaemia + low platelets + kidney injury.
- The common cause in children: STEC (O157:H7) after bloody diarrhoea.
- Treatment is supportive; dialysis as needed.
- No antibiotics and no loperamide in STEC diarrhoea.
- Atypical HUS: complement → eculizumab; pneumococcal: positive Coombs.
Summary table
| Type | Background | Features | Treatment |
|---|---|---|---|
| Typical HUS (STEC) | Toddlers, bloody diarrhoea about 5–10 days earlier | Haemolysis with schistocytes, low platelets, kidney injury; normal complement | Supportive: careful fluids, dialysis as needed, red-cell transfusion for severe anaemia |
| Pneumococcal HUS | Pneumococcal pneumonia or meningitis | Positive direct Coombs | Antibiotics; washed blood products; avoid plasma |
| Atypical HUS (complement) | No diarrhoea, recurrent, family history | Sometimes low C3 | Eculizumab (a C5 inhibitor) |
| TTP (for contrast) | Rare in children | ADAMTS13 below 10%; fever and neurological signs | Plasma exchange; in the congenital form — plasma or recombinant ADAMTS13 |
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Sources
- Nelson Textbook of Pediatrics, 22nd edition (2024) — Hemolytic-Uremic Syndrome
- KDIGO Controversies Conference report: Atypical hemolytic uremic syndrome and C3 glomerulopathy, 2017 — Diagnosis and complement-inhibitor treatment
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.