Hemolytic Uremic Syndrome in Children

The term hemolytic uremic syndrome (HUS) describes a heterogenous group of diseases characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and renal failure. Diarrhea-associated HUS (D+ HUS) accounts for 90 % of cases in childhood, and it is one of the most frequent causes of acute renal failure in children less than five years of age leading to a significant degree of morbidity and mortality. The first step in the pathogenesis of D+HUS is the local inflammation of the intestinal epithelium and endothelium due to Shigatoxin (Stx) producing E. coli infection. This leads to intestinal hemorrhagie, loss of barrier functions, and generation of inflammatory cytokines. Together with TNFα and E.coli derived lipopolysaccharide Stx may act synergistically to damage vascular endothelium. Vascular endothelial injury and its consequences may lead to permanent damage of the kidney, brain, heart, pancreas, and necrosis of intestine. In contrast to D+HUS, the atypical HUS is not associated with diarrhea. Familial and recurrent form of HUS may be associated with low C3 complement levels and/or genetic mutations in factor H. The main purpose of this article is to review the epidemiological, pathogenetic, and clinical features, current treatment strategies, and outcome of D+ HUS with a brief focus on atypical HUS.