Paediatrics: Haemolytic–uraemic syndrome

Haemolytic–uraemic syndrome

This is the commonest cause of AKI in children in Europe and the USA. It typically has a seasonal variation with peaks in the summer and autumn months. It presents with a triad of:

·  microangiopathic haemolytic anaemia;

·  thrombocytopenia;

·  acute renal failure.

Two forms of HUS are recognized.

·  Atypical/sporadic:

o not diarrhoea-associated (D^– HUS);

o often familial.

·  Epidemic form:

o diarrhoea-associated (D⁺ HUS);

o commonly associated with verocytotoxic producing E. coli 0157.

H7 type, although other pathogens have also been implicated (e.g. Shigella, Streptococcus pneumoniae).

E.coli are common bacteria, normally found in the gut of warm-blooded animals. There are many types of E. coli, most of which are harmless. However, the enterohaemorrhagic E. coli (EHEC) produce toxins (poi-sons) that can cause gastroenteritis with blood in the stool. The toxins are called shiga toxins or verotoxins; hence, EHEC is also called STEC or VTEC. VTEC is found in the gut of cattle, and can also be found in the gut of humans without causing illness. The bacteria can be passed on to humans by:

·  Eating improperly cooked beef, in particular, ground or mince beef.

·  Drinking raw (unpasteurized) milk.

·  Close contact with a person who has the bacteria in their faeces.

·  Drinking contaminated water.

·  Swimming or playing in contaminated water.

·  Contact with farm animals.

Clinical features

Acute renal failure

Gut

·  Prodrome of bloody diarrhoea.

·  Rectal prolapse.

·  Haemorrhagic colitis.

·  Bowel wall necrosis and perforation.

Pancreas (occurs in <10%)

·  Glucose intolerance/insulin-dependent diabetes mellitus.

·  Pancreatitis.

·  Liver jaundice.

·  Neurological Irritability to frank encephalopathy.

Cardiac myocarditis (rare)

Investigations

·FBC + film.

·Blood cultures.

·U&E.

·LFTs.

·E. coli polymerase chain reaction (PCR).

·Stools: microscopy and culture.

Treatment

Early liaison with a paediatric nephrology unit is required, as early dialysis may be needed. Management is mainly supportive and directed at treating the clinical features of HUS. Antibiotics for underlying E. coli infection are not indicated.

·Monitor electrolyte balance.

·Monitor fluid balance.

·Nutrition.

·Blood transfusion (note risks/concerns regarding fluid overload and hyperkalaemia).

·Treat hypertension.

Outcome

·Generally good.

·Mortality <5%.

Long-term: up to 30% may develop mild impairment of GFR.