Hemolytic uremic syndrome (HUS)

DEFINITION

Hemolytic uremic syndrome (HUS) is a condition that results from the abnormal premature destruction of red blood cells. Once this process begins, the damaged red blood cells start to clog the filtering system in the kidneys, which may eventually cause the life-threatening kidney failure associated with hemolytic uremic syndrome.

Most cases of hemolytic uremic syndrome develop in children after two to 14 days of diarrhea — often bloody — due to infection with a certain strain of Escherichia coli (E. coli). Adults also may develop hemolytic uremic syndrome after an E. coli infection, but the cause also may be certain medications, other types of infections, pregnancy or it may be 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.

CAUSES

A number of things can cause hemolytic uremic syndrome, but the most common cause — particularly in children — is an infection with a specific strain of E. coli, usually the strain known as O157:H7. However, other strains of E. coli have been linked to hemolytic uremic syndrome, too.

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 some strains of E. coli are responsible for serious foodborne infections, including those that can lead to hemolytic uremic syndrome. E. coli may be found in:

• Contaminated meat or produce
• Swimming pools or lakes contaminated with feces

Most people who are infected with E. coli, even the more dangerous strains, won’t develop hemolytic uremic syndrome. It’s also possible for hemolytic uremic syndrome to follow infection with other types of bacteria.

In adults, hemolytic uremic syndrome is more commonly caused by other factors, including:

• The use of certain medications, such as quinine (an over-the-counter muscle cramp remedy), some chemotherapy drugs, the immunosuppressant medication cyclosporine (Neoral, Sandimmune) and anti-platelet medications
• Pregnancy
• Certain infections, such as HIV/AIDS or an infection with the pneumococcal bacteria
• Genes, which can be a factor because a certain type of HUS — atypical hemolytic uremic syndrome — may be passed down from your parents

The cause of hemolytic uremic syndrome in adults is often unknown.

SYMPTOMS

Signs and symptoms of hemolytic uremic syndrome may include:

• Bloody diarrhea
• Vomiting
• Abdominal pain
• Pale skin tone
• Fatigue and irritability
• Fever, usually not high and may not be present at all
• Blood in the urine
• Small, unexplained bruises or bleeding from the nose and mouth
• Decreased urination or blood in the urine
• Swelling of the face, hands, feet or entire body
• Confusion

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, bloody diarrhea, unusual bleeding, swollen limbs, extreme fatigue or decreased urine output after several days of diarrhea. Seek emergency care if you or your child doesn’t urinate for 12 hours or more.