Typical and atypical hemolytic uremic syndrome

The hemolytic uremic syndrome is the most frequent cause of acute renal failure in childhood. In the vast majority of patients, the syndrome of acute hemolysis, thrombopenia and renal dysfunction is preceded by an episode of diarrhea with or without bloody stools. This colitis is caused by different strains of Escherichia coli which produce shiga like toxins. These toxins are responsible for both hemolysis and renal disease. There are good reasons for distinguishing patients with D (+) HUS and those without prodromal diarrhea [D (-) HUS], especially since the outcome in the latter group is less predictable and on average fairly unfavorable. D (+) HUS has also been labeled 'typical HUS' and D (-) HUS as 'atypical HUS'. This has led to some oversimplification, in that atypical has become synonymous with poor outcome. Our experience comprises 20 D (-) HUS patients, of whom 14 did extremely well. Scrutinizing the data of our patients lead to the conclusion that, within the D (-) group, some have a 'typical course' and display complete cure whereas those with an 'atypical course' either die or have severe sequelae.