What is hemolytic uremic syndrome?

Causes and Symptoms

In the majority of cases, hemolytic uremic syndrome develops after the digestive system has been infected by the O157:H7 strain of Escherichia coli (E. coli).
Undercooked meats, contaminated fresh vegetables and fruits, unpasteurized dairy products and juices, and contaminated water are the primary sources of this bacterium. Hemolytic uremic syndrome can be passed from person to person. Less common sources include Shigella, Salmonella, Yersinia, and Campylobacter bacteria.

Following a siege of gastroenteritis
that typically lasts for three to ten days and usually includes vomiting, fever, cramping, and diarrhea, hemolytic uremic syndrome develops when the E. coli produce toxins that enter the bloodstream and begin destroying red blood cells and platelets. The damaged red blood cells block tiny blood vessels in the kidneys, making it more and more difficult for the kidneys to function. Resulting symptoms can include reduced urine output, paleness, small body bruises, blood in the urine and stool, extreme fatigue, irritability, seizures, increased blood pressure, and swollen limbs.

Treatment and Therapy

Once an individual is diagnosed with hemolytic uremic syndrome, the typical treatment is mostly supportive. Maintaining normal electrolyte and water levels in the body eases the immediate symptoms and helps prevent further complications. Vital signs are monitored frequently, as is the weight of the patient. Blood transfusions are necessary only when there is severe anemia.

Depending on urine output and electrolyte abnormalities, dialysis
may be used. On rare occasions, the victim may require a kidney transplant. Administration of antimotility agents, antibiotics, or platelet transfusions seems to worsen the outcome.

Perspective and Prospects

Hemolytic uremic syndrome was first described by Swiss hematologist Conrad von Gasser in 1955. Although it is an uncommon illness, striking examples exist in which many individuals have been infected during a particular time frame. In 2000, more than two thousand people developed hemolytic uremic syndrome symptoms after drinking contaminated water in Walkerton, Ontario, Canada; seven died. Three months later, forty individuals experienced hemolytic uremic syndrome symptoms after eating at a Sizzler restaurant in Milwaukee, Wisconsin; one died. In 2006, more than 180 individuals were identified with hemolytic uremic syndrome symptoms in the United States as a result of contaminated spinach grown in California; three died. In 2011, fenugreek seeds contaminated with E. coli O104:H4 caused an epidemic of hemolytic uremic syndrome, affecting 3,800 people, most of whom were adults; thirty-six died.

Research into treating hemolytic uremic syndrome has focused on preventing its onset by using chemical agents that bind the toxins produced by E. coli O157:H7 within the intestines. Strategies involving immunization are also being developed.

Bibliography

Boyer, Olivia, and Patrick Niaudet. "Hemolytic Uremic Syndrome: New Developments in Pathogenesis and Treatment." International Journal of Nephrology, August 2011.

Buchholz, Bernard, et al. "German Outbreak of Escherichia coli O104:H4 Associated with Sprouts." New England Journal of Medicine 365, no. 19 (2011): 1763–70.

Hoffman, Ronald, et al., eds. Hematology: Basic Principles and Practice. 5th ed. Philadelphia: Churchill Livingstone/Elsevier, 2009.

Kaper, James B., and Alison D. O’Brien, eds. Escherichia coli O157:H7 and Other Shiga Toxin-Producing “E. coli” Strains. Washington, D.C.: ASM Press, 1998.

Parker, James N., and Philip M. Parker, eds. The Official Patient’s Sourcebook on Hemolytic Uremic Syndrome: A Revised and Updated Directory for the Internet Age. San Diego, Calif.: Icon Health, 2002.

Tintinalli, Judith E. Emergency Medicine: A Comprehensive Study Guide. 7th ed. New York: McGraw-Hill, 2011.