Hemolytic uremic syndrome (HUS) is an uncommon, but serious condition that can cause life-threatening kidney failure. Hemolytic uremic syndrome most often affects children and older adults.

In children, most cases of hemolytic uremic syndrome develop after several days of diarrhea — often bloody — due to infection with a specific strain of Escherichia coli (E. coli). Adults also may develop hemolytic uremic syndrome after an E. coli infection, but more often the cause is obscure or even unknown.

Though hemolytic uremic syndrome is a serious condition, getting timely and appropriate treatment leads to a full recovery for most people — especially young children.

Signs and symptoms of hemolytic uremic syndrome may include:

• Fever
• Abdominal pain
• Pale skin tone
• Fatigue and irritability
• Small, unexplained bruises or bleeding from the nose and mouth
• Decreased urination
• Swelling of the face, hands, feet or entire body

Sometimes neurological symptoms, such as seizures, develop as well.

When to see a doctor
Call your doctor immediately if you or your child experiences unexplained bruises, unusual bleeding, swollen limbs, extreme fatigue or decreased urine output after several days of diarrhea. Seek emergency care if you or your child goes 12 hours without urinating.

In children, most cases of hemolytic uremic syndrome develop after infection with a specific strain of E. coli known as O157:H7.

E. coli refers to a group of bacteria normally found in the intestines of healthy humans and animals. Of the hundreds of types of E. coli, most are harmless. But a few strains of E. coli are responsible for serious food-borne infections, including those that can lead to hemolytic uremic syndrome. E. coli is found in:

• Unwashed produce or undercooked meat (most often)
• Swimming pools or lakes contaminated with feces

Not all strains of disease-causing E. coli bacteria are created equal. For example, the strain of E. coli responsible for most cases of traveler's diarrhea often runs its course in just a few days. Even most people affected by the more virulent E. coli O157:H7 recover completely within five to 10 days. Progression to hemolytic uremic syndrome is uncommon.

It's also possible for hemolytic uremic syndrome in children to follow infection with other types of bacteria, including shigella, salmonella, yersinia and campylobacter.

In adults, hemolytic uremic syndrome is more likely to be caused by an autoimmune disease, a blood infection or the use of certain medications. More often, however, the cause of hemolytic uremic syndrome in adults is obscure or even unknown.

Hemolytic uremic syndrome is most common in children under 10 years of age. People who have immature or weak immune systems — such as young children and older adults — have the highest risk of developing hemolytic uremic syndrome after an E. coli infection.

According to the National Institutes of Health, about half the people who develop hemolytic uremic syndrome experience sudden kidney failure. In fact, hemolytic uremic syndrome is the most common cause of sudden (acute) kidney failure in children. High blood pressure, chronic kidney failure, heart problems, stroke and coma are possible as well.

Because most people with hemolytic uremic syndrome are admitted to the hospital after a trip to the emergency room or following a brief phone call or visit with their doctor, it's not likely that you or your child will have a routine office visit.

However, if you or your child is experiencing symptoms of hemolytic uremic syndrome after several days of diarrhea, call your doctor immediately and be prepared to answer these questions:

• Have you noticed blood in you or your child's diarrhea?
• What other symptoms — such as fever, swelling or decreased urine — have you or your child experienced?
• How long have you or your child been experiencing these symptoms?
• How long has it been since you or your child urinated?

If your doctor suspects hemolytic uremic syndrome, various lab tests may be done to confirm the diagnosis. Blood tests may reveal a low platelet count, low red blood cell count or a higher than normal level of creatinine — a breakdown product of creatine, an important part of muscle — in your blood. Your doctor may also collect a urine sample to test for blood in your urine.

Hemolytic uremic syndrome requires careful management in the hospital. To ease immediate signs and symptoms and prevent further problems, hemolytic uremic syndrome treatment may include:

• Red blood cell transfusions. If you don't have enough red blood cells, you may feel chilled, fatigued and short of breath. You may have a rapid heart rate, yellow skin and dark urine. Red blood cell transfusions, given through an intravenous (IV) needle, may help reverse these signs and symptoms.
• Platelet transfusions. If you're bleeding or bruising easily, platelet transfusions can help your blood to clot. Like red blood cell transfusions, platelet transfusions are given through an IV needle.
• Plasma exchange. Plasma is the part of blood that supports the circulation of blood cells and platelets. Sometimes a machine is used to clear the blood of its own plasma and replace it with fresh or frozen donor plasma.
• Kidney dialysis. Sometimes dialysis is needed to filter waste and excess fluid from the blood. Dialysis is usually a temporary treatment until the kidneys begin functioning adequately again. If the kidney damage is significant, however, permanent kidney failure — requiring long-term dialysis or a kidney transplant — is possible.

Despite the severity of the condition, appropriate treatment leads to a full recovery for most people with hemolytic uremic syndrome — especially young children.

Specific preventive measures for hemolytic uremic syndrome aren't clear. However, it's always a good idea to protect yourself — and your children — from E. coli infection:

• Wash your hands, utensils and food surfaces often.
• Keep raw foods separate from ready-to-eat foods.
• Defrost raw meat in your microwave or refrigerator. (Don't leave meat on the counter to thaw.)
• Thoroughly cook ground beef to at least 160 F (71 C). (Hamburgers should be well-done.)
• Wash fruits and vegetables under running water.
• Avoid unpasteurized milk, juice and cider.
• Avoid swimming in water potentially contaminated with feces.

Also make sure that everyone in your family — including children — washes his or her hands after using the toilet or changing diapers and before eating. In child care facilities, diapers shouldn't be changed or disposed of in the same room where food is prepared or eaten.