Hemolytic uremic syndrome: epidemiology, pathophysiology, and therapy
Hemolytic uremic syndrome: epidemiology, pathophysiology, and therapy. Andreoli SP, Trachtman H, Acheson DWK, Siegler RL, Obrig TG. Pediatric Nephrology 2002;17:293-298.
This paper is based on the proceedings of the American Society of Pediatric Nephrology Educational Symposium that took place in May 2000 in Boston, Massachusetts (and therefore reflect the medical community’s knowledge of hemolytic uremic syndrome [HUS], at that time). A large portion of this paper explains the pathophysiology of E. Coli O157:H7 and HUS, both in animal models and in humans. The specifics of how cell injury occurs in the kidney as a result of Shiga toxin-producing E. Coli (STEC) is also detailed, and is critical to understanding the rationale for specific treatments. Briefly, recent data suggest that a local renal inflammatory burst may be an early event in HUS. In addition, enzymes generated in the kidney are likely to activate specific cells to express receptors so that they can bind and respond to the Shiga toxins (Stx) and to make the cell surfaces more prothrombotic and adherent for neutrophils. Stx may also indirectly activate platelets but more thorough analyses must be conducted before a mechanism can be assigned. In terms of therapy, it is noted that the following have been adequately tested and are probably of no value: anticoagulants such as heparin or prostacyclin, fibrinolytics such as streptokinase, intravenous gamma-globulin (IgG), plasma infusion, and steroids. In contrast, the use of antiplatelet drugs such as aspirin or dipyridamole, high-dose intravenous infusions of furosemide, and plasmapheresis have not been sufficiently assessed and are of questionable value. Although efficacy is not clear, many pediatric nephrologists continue to utilize these treatments. The only new drug that is currently undergoing evaluation in children with HUS is SYNSORB Pk. It is designed to prevent systemic absorption of Stx. Potential new therapies that are still undergoing testing in animals include monoclonal antibodies to Stx2 and administration of vascular endothelial growth factor. The use of vaccines is also under consideration. Finally, the data regarding the impact of antibiotic use on the development of HUS are mixed. Currently, there is no proven therapy for diarrhea-associated HUS and clinical research is needed to design treatments that can safely and effectively reduce the serious consequences of this life-threatening disease.