Hemolytic uremic syndrome.

HUS has now emerged as a common clinical and pathologic syndrome that may result from a variety of disease processes. On the basis of clinical and epidemiologic criteria, several distinct subgroups of the disorder have been distinguished, the most common of which are the result of infectious processes, whereas the rarer forms may be genetically determined or acquired defects in vascular homeostasis. A related group of bacterial toxins, verotoxins, and Shiga toxin, produced by a variety of species of enteric pathogens, have been implicated in the pathogenesis of typical childhood HUS. In the few years since verotoxin-producing organisms were first incriminated as the possible etiologic agents of HUS, there has been a remarkable growth in knowledge of the biology of verotoxin and its role, not only in HUS but in hemorrhagic colitis and childhood diarrhea. The availability of purified toxin and new tools for detection of verotoxin and verotoxin-producing organisms, such as monoclonal antibodies and probes for DNA hybridization, should enable definitive studies of the epidemiology and pathogenesis of verotoxin-associated HUS to be undertaken. The growing understanding of HUS should eventually lead to improved treatment and ultimately to prevention of this serious childhood disorder.