Diarrhoeal-associated haemolytic uraemic syndrome

Diarrhoeal-associated HUS is a common cause of acute renal failure, particularly in young children. The diagnosis is made by the presence of the following triad of findings: haemolytic anaemia (< 10 g/dl), thrombocytopenia (< 150x10(9)/l) and a creatinine value that is above the upper limit of normal for age. Ninety per cent of cases follow a diarrhoeal prodrome, and of these the majority are due to enterohaemorrhagic E. coli or VTEC. Sporadic and epidemic cases occur and sources of infection include undercooked meat, contact with farm animals and their faeces, and contaminated water, fruit, or vegetables. Typically, children under three years of age are affected and present with abdominal pain and diarrhoea. The diarrhoea is often watery and soon becomes bloody. There may also be vomiting. The diarrhoea lasts on average for eight days, and the colitis can be so severe that children may present with an acute abdomen. Perforation, bowel infarction, and intussusception are rare complications. Rectal prolapse is a more common complication. Diagnosis of VTEC infection is by stool culture and serology. Ten per cent of patients with VTEC infection go on to develop HUS. Of these, 50-60% will develop acute renal failure requiring dialysis. Extrarenal manifestations include seizures and somnolence, with cerebral infarcts and oedema being less common complications. Pancreatitis and altered glucose tolerance can occur and cardiac ischaemia has been reported. On average, dialysis is required for 8-10 days; those requiring dialysis for longer than four weeks are unlikely to make a full renal recovery. Acute mortality is 5-10%, being more common in patients with neurological involvement. End-stage renal failure develops in 3-5%, and up to 25% may be left with renal impairment. At one year after the illness, a normal GFR, normal BP, and absence of proteinuria are predictive of a complete recovery.