Hemolytic Uremic Syndrome
Charles L. Stewart MD1
Leticia U. Tina MD2
1 Assistant Professor of Pediatrics, Pediatric Nephrology, SUNY Stony Brook School of Medicine, Stony Brook, NY.
2 Associate Professor of Pediatrics, Pediatric Nephrology, Georgetown University School of Medicine, Washington, DC.
The hemolytic uremic syndrome (HUS), a heterogeneous group of disorders characterized by microangiopathic hemolytic anemia, thrombocytopenia, and azotemia, is the most frequent cause of acute renal failure in children. The pathologic findings of endothelial damage in small-to-medium size arteries, with localized fibrin deposition and thrombotic microangiopathy, are similar to the vasulopathy seen in thrombotic thrombocytopenic purpura (TTP), and many clinical features are shared by both syndromes. HUS and UP may represent the same underlying pathophysiology but have differing end organ manifestations. In HUS, the kidney is the principal organ involved; patients who have TTP have more prominent central nervous system (CNS), heart, pancreas, and spleen involvement but also may have renal involvement. This has prompted many investigators to incorporate the terms HUS/TTP when referring to this group of microangiopathies. Recent studies have delineated distinct subgroups of HUS and have implicated certain toxin-producing serotypes of Escherichia coli as an etiologic agent in the more common subgroup of HUS. After discussing the epidemiology and classification of HUS, this article will review recent information regarding the pathogenesis, diagnosis, and management of the disorder.
Epidemiology/Classification
HUS occurs throughout the world, with certain countries (South Africa, Holland, and Argentina) reporting a higher incidence than others. The prevalence of HUS in Argentina is estimated to be 30 cases per 100 000 children; estimates of prevalence in the United States range from 0.3 to 10 cases per 100 000 children.
