By Silvia German, RN, CNN, Education Manager with the DaVita® National Clinical Education Team
Hemolytic uremic syndrome (HUS) involves three disease processes:
There are two variations of HUS. D+HUS is preceded by a gastrointestinal infection and D-HUS has different causes. D-HUS is less common, while D+HUS accounts for 95 percent of all cases.
D+HUS occurs predominantly in children between the ages of 6 months and 4 years. Adults older than 60, or those with an impaired immune system, are also at greater risk of developing HUS. Both sexes and all races are equally affected.
D+HUS follows a gastrointestinal infection with a strain of shiga toxin-producing Escherichia coli (E. coli) bacteria. The majority of E. coli strain is harmless and normally present in the gut of humans and warm-blooded animals. Shiga toxin-producing E. coli, however, are not normal in the human gut and release a poisonous substance that causes diarrhea, intestinal bleeding and damage to the bowel walls. After entering the bloodstream through the gastrointestinal mucous membranes, shiga toxin can cause damage to the thin layer of cells that line the inside of small blood vessels causing them to clot.
Shiga toxin can also be directly toxic to kidney cells. This process sets the syndrome in motion. The large amount of platelets used to promote clotting causes thrombocytopenia in the overall blood supply, with bruising and bleeding elsewhere in the body. The partially obstructed small blood vessels, including those within the kidneys, damage RBCs trying to pass through, causing hemolytic anemia. Finally, the decrease in blood supply and oxygen to the kidneys causes acute renal failure.
If a gastrointestinal infection after several days of diarrhea progresses to HUS, signs and symptoms may include:
Along with a physical exam, laboratory tests are used to diagnose HUS. Here are some things a physician looks for when identifying this condition:
Due to its severity, HUS is usually treated in the hospital. Treatment may include some or all of the following:
The E. coli strain producing shiga toxin is found in 1 percent of healthy cattle and their meat may become contaminated during processing. Other ways of contracting the disease include:
Prevention is therefore based on good personal hygiene, including frequent and thorough hand washing. Kitchen rules should include keeping cooking utensils and surfaces clean, cooking meat well enough to destroy viable bacteria, washing fruits and vegetables under running water, and drinking milk, juice or cider that is pasteurized.
It is estimated that D+HUS affects about two in every 100,000 people per year, with peak outbreaks between the months of June and September. Complications can be severe, including chronic kidney failure, heart problems, strokes and coma. Death is usually linked to a non-renal-related problem. However, with timely and appropriate treatment, the survival rate in D+HUS is significantly high. While approximately two-thirds of children with D+HUS require short term dialysis, most regain kidney function and recover fully.
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Please check with a physician if you need a diagnosis and/or for treatments as well as information regarding your specific condition. If you are experiencing urgent medical conditions, call 9-1-1