Haemolytic Uraemic Syndrome

Haemolytic uraemic syndrome (HUS) is a thrombotic microangiopathy: injury to the lining of small blood vessels, particularly within the kidneys, with tiny clots forming inside them. Picture the smallest vessels turning into a narrow, damaged, partly clogged mesh. Almost everything else about HUS follows from that one picture. Red blood cells forced through the mesh are torn apart. Platelets are used up building the clots. The kidney, which depends on those small vessels to filter blood, loses perfusion and function. That gives the classic triad: 1. Microangiopathic haemolytic anaemia. 2. Thrombocytopenia. 3. Acute kidney injury (AKI). The child in front of you usually does not look like three lab abnormalities. The child looks pale, bruised, tired and is passing little urine, often days after a bout of bloody diarrhoea that the family thought was ending. HUS is mainly a disease of young children, and it is a leading cause of AKI in childhood. It can progress rapidly to kidney failure, neurological complications and severe electrolyte disturbances, so recognizing the pattern early changes what happens next. About half of children with...