Hemolytic uremic syndrome

Haemolytic uraemic syndrome (HUS) is a multisystem thrombotic microangiopathic disease characterised by the triad of renal failure, haemolytic anaemia and thrombocytopenia. It is the most common cause of renal failure in infancy and childhood requiring dialysis. 

There are two forms of this syndrome:

• typical or D+ HUS: corresponds to >90% of all HUSinstances, occurs in childhood, and is caused by Shiga toxin-producing Escherichia coli
• atypical or D- HUS: can occur after infections, use of certain drugs, following other pathologies (e.g. malignancy), or, rarely, due to defective cobalaminvitamin B₁₂ metabolism ³

This article is based on the features related to the typical HUShaemolytic-uraemic syndrome. 

Epidemiology

HUSHaemolytic-uraemic syndrome affects ~ 2:100,000 people worldwide ³.

Clinical presentation

It It is most commonly seen in young children.

Usually, there is an interval of 2-12 days between the ingestion of contaminated food and the first day of diarrhoea and abdominal pain. After 1-3 days the diarrhoea becomes bloody (~90%). Fever is usually absent.

Pathology

HUS usuallyIn over 90% of cases, haemolytic-uraemic syndrome occurs (>90%) followingfollowing a gastrointestinal infection with Shiga toxin-producing E. coli (STEC). Some cases are associated with medical conditions such as collagen vascular conditions like SLEdiseases, such as systemic lupus erythematosus, underlying malignancy, or medications such as cyclosporine, OCPoral contraceptives, or 5 FU-fluoro-uracyl.

Injury to the endothelium of the capillaries results in mechanical destruction of the RBCserythrocytes. KidneysThe kidneys can be the only organ involved; however, involvement of the other organ likeorgans, such as liver, pancreas, heart, intestine, and muscles, is also possible.

Radiographic features

MRI

Bilateral, often symmetric, basal ganglia (especially putamen) and centrum semiovale hyperintensity on T2/FLAIR images, usually due to vasogenic edema.

Foci of diffusion restriction may sometimes be found, especially in the acute phase.

History and etymology

The term was coined by the Swiss doctorphysician Conrad von Gasser in 1955. The relation of E. coli as as an aetiological factor was proposed by Mohamed A. Karmali in 1985 ^2,4.

MRI Findings

Bilateral , often symmetric basal ganglia (esp Putamen)

Shiga toxin is named after Japanese physician and centrum semiovale hyperintensity on T2/ FLAIR imagesbacteriologist Kyoshi Shiga, usually due to vasogenic edemaas is the genus Shigella.