Hemolytic Uremic Syndrome

Hemolytic uremic syndrome (HUS) is a condition that affects blood vessels in your kidneys. It damages your kidneys and may cause blood clots. E.coli is the most common cause of HUS. In most cases, symptoms include diarrhea, abdominal pain, high blood pressure and low urine output. Treatment includes IV fluids, IV blood plasma and medications.


What is hemolytic uremic syndrome?

Hemolytic uremic syndrome (hee-mah-lit-ick yer-ee-mik sin-drohm) is a medical condition that blocks the small blood vessels in your kidneys. The blockage destroys your red blood cells (hemolytic anemia) and reduces the number of platelets (thrombocytopenia), which are clotting cells. Hemolytic uremic syndrome (HUS) most commonly affects your kidneys.

What is atypical hemolytic uremic syndrome?

Atypical hemolytic uremic syndrome (aHUS) is a rare type of HUS. Its features include low levels of red blood cells, a low platelet count and acute kidney failure.

Atypical hemolytic uremic syndrome is typically a genetic condition, which means birth parents pass it down to their children. Mutations in some of your genes that encode proteins cause aHUS. Another illness, an infection or an environmental factor triggers the mutation to activate.


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Who does hemolytic uremic syndrome affect?

Anyone can develop HUS. However, you’re more likely to develop it if you:

  • Are under five years old.
  • Have a weakened immune system.
  • Have a family history of HUS.
  • Get Escherichia coli (E. coli) bacteria, usually from eating undercooked meat or unpasteurized milk.
  • Have direct contact with someone who has diarrhea due to E. coli.

How common is hemolytic uremic syndrome?

Hemolytic uremic syndrome has a prevalence of between 5% and 15% in people who have E. coli.

Symptoms and Causes

What are the symptoms of hemolytic uremic syndrome? What happens in hemolytic uremic syndrome?

Hemolytic uremic syndrome symptoms include:

In severe cases of HUS, damaged red blood cells can clog the tissue in your kidneys. As a result, your kidneys can’t filter and eliminate waste from your body. If your kidneys can’t filter and eliminate waste, it can lead to acute kidney injury.

Symptoms of acute kidney injury include:

  • Decreased urine (pee) output (oliguria).
  • Blood in your pee.
  • Feeling sick, caused by an increase in your blood toxin levels.
  • High blood pressure (hypertension).
  • Shortness of breath (dyspnea).
  • Swelling (edema) in your legs, feet or ankles, and less often in your face, hands or elsewhere in your body.

If I have diarrhea, do I have hemolytic uremic syndrome?

If you have diarrhea, it doesn’t mean you have HUS. However, you should seek medical attention if you have bloody diarrhea or severe diarrhea (when you can’t stay hydrated, or it lasts longer than three days).


What is the classic triad associated with hemolytic uremic syndrome?

A medical triad is a group of three signs that indicate a medical condition.

The classic triad associated with HUS includes damage to your red blood cells (microangiopathic hemolytic anemia), a steady decrease in the number of platelets in your blood (thrombocytopenia) and acute kidney injury.

What is the main cause of hemolytic uremic syndrome?

Certain strains of the bacteria E. coli cause most cases of hemolytic uremic syndrome. These strains of E. coli make you sick by producing a toxin called Shiga. Shiga damages the lining of your small intestines and causes diarrhea. It can also enter your bloodstream, destroy red blood cells and damage your kidneys.

Another name for these strains is Shiga toxin-producing E. coli (STEC). The most common STEC in North America is E. coli O157:H7, or E. coli O157.

Rarely, certain medications may cause HUS.

How do I get E. coli?

E. coli usually enters your body when you eat spoiled, undercooked or poorly processed foods or drinks. These may include:

  • Undercooked meat (usually ground beef).
  • Unpasteurized milk or fruit juice.
  • Unwashed and contaminated raw fruits and vegetables.

E. coli can also spread from person to person through an oral-fecal route. “Oral-fecal” means that harmful strains of E. coli spread when people don’t wash their hands thoroughly with soap and water after they use the bathroom or touch feces (poop). You may touch poop after changing diapers or incontinence garments. You may also touch poop after petting zoo or farm animals that have soiled fur. If you have harmful E. coli bacteria on your hands, it can enter your system when it transfers to the food you eat, or you put your fingers in your mouth.


Is hemolytic uremic syndrome contagious?

HUS isn’t contagious. You can’t get HUS from person-to-person contact.

However, you can get E. coli after consuming contaminated food or drinks or contact with a contaminated person’s or animal’s poop.

Diagnosis and Tests

How do you know if you have hemolytic uremic syndrome?

Your healthcare provider will diagnose hemolytic uremic syndrome. They’ll ask you about your medical history and family medical history. They’ll also conduct a physical exam and order tests.

What tests will be done to diagnose hemolytic uremic syndrome?

Your healthcare provider may order the following tests:

  • Urine test. You’ll pee into a special container. Then, a healthcare provider will place a strip of paper coated with special chemicals (dipstick) into the container. The dipstick will change color if there is protein or blood in your pee.
  • Blood test. Your healthcare provider will use a small needle to draw a blood sample from a vein in your arm.
  • Genetic testing. Your provider may send part of your blood sample to a lab for genetic testing. Genetic testing determines whether you have higher odds of developing HUS according to your genes (genetic tendency). This helps determine how long you may need therapies such as eculizumab or ravulizumab. If you have a genetic abnormality, you have a higher chance of requiring long-term therapy with eculizumab or ravulizumab.
  • Stool test. Your healthcare provider will give you a special container and a disposable spoon. The next time you have to poop, you’ll place plastic wrap or newspaper across the rim of your toilet to collect your poop. You can also poop into a different container. You’ll then use the disposable spoon to collect a small sample, put it in the special container and return it to your healthcare provider.
  • Kidney biopsy. Your healthcare will provide a small piece of your kidney tissue to examine at a lab under a microscope. Your healthcare provider will first numb the area with a local anesthetic so you won’t feel any pain. They’ll also give you a light sedative to help you relax. Then, they’ll insert a needle through your skin and into your kidney to collect the tissue sample. Kidney biopsies are rarely necessary for adults. Children don’t need kidney biopsies.

Which findings indicate hemolytic uremic syndrome?

Tests look for the presence of different things that indicate hemolytic uremic syndrome.

Urine tests look for blood or protein in your pee. Blood tests detail your red blood cell levels and platelet levels. They can also tell your healthcare provider how well your kidneys and liver are functioning. Stool tests check for the presence of E. coli O157. A kidney biopsy shows damage to your kidney.

Management and Treatment

How is hemolytic uremic syndrome treated?

Hemolytic uremic syndrome treatment may include blood transfusions, especially red blood cells and platelets. Red blood cells help with signs and symptoms of anemia, including chills, fatigue, shortness of breath and rapid heart rate. Platelets help your blood clot, especially if you’re bleeding or bruising easily.

You may have a greater chance of getting an infection during treatment, so it’s a good idea to wash your hands often and distance yourself from people with infections, including a common cold or the flu.

Your healthcare provider may also give you intravenous (IV) fluids to keep you hydrated.

If you have severe kidney failure, you may need dialysis to keep your blood clean while your kidneys heal. Dialysis is usually temporary.

What medications are used to treat hemolytic uremic syndrome?

If you have high blood pressure due to kidney failure, you may have to take medications to bring it down.

If you have atypical hemolytic uremic syndrome, your healthcare provider may prescribe eculizumab or ravulizumab to help prevent blood clots from damaging your blood vessels, blood cells and kidneys.

Eculizumab and ravulizumab increase your chances of developing meningococcal disease and pneumococcal disease. Your provider will prescribe meningococcal and pneumococcal vaccinations before starting the medications. They may also prescribe antibiotics for at least two weeks.

Talk to your provider if you’re pregnant, planning on getting pregnant or breastfeeding before taking eculizumab or ravulizumab. You must be aware of the benefits and risks to you and your baby.

Can you recover from hemolytic uremic syndrome?

Yes, you can recover from hemolytic uremic syndrome. If you have HUS, you can recover without permanent damage to your health.

Children have an easier time recovering from HUS than adults. More than 85% of people with HUS recover complete kidney function.

However, even with full recovery, you may have high blood pressure or other kidney problems in the future.


How can I prevent hemolytic uremic syndrome?

The following tips can help you prevent HUS due to E. coli O157:

  • Avoid unsanitary swimming areas.
  • Avoid swimming if you have diarrhea.
  • Avoid drinking unpasteurized drinks, including milk, cider and juice.
  • Clean kitchen utensils (knives, spatulas, tongs, spoons and so on) and food surfaces (cutting boards, countertops, plates and so on) regularly.
  • Cook meat to an internal temperature of at least 160 °F (71 °C).
  • Defrost meat in the microwave or refrigerator, not on a food surface or in warm water.
  • Separate raw foods from cooked foods.
  • Wash your hands before eating.
  • Wash your hands after changing diapers, changing incontinence garments and using the restroom.
  • Wash your hands after petting farm animals.

Outlook / Prognosis

What can I expect if I have hemolytic uremic syndrome?

With proper diagnosis and care, most people with HUS recover without permanent damage to their health. If you don’t treat HUS, it can be fatal.

Living With

When should I see my healthcare provider?

Contact your healthcare provider if you have:

  • Bloody diarrhea.
  • Diarrhea that lasts longer than three days.
  • Low amounts of pee when you go to the bathroom.
  • Swelling.
  • Easily bruised skin.
  • Fatigue.

What questions should I ask my healthcare provider?

  • How do you know that I have hemolytic uremic syndrome?
  • How did I get hemolytic uremic syndrome?
  • If I don’t have hemolytic uremic syndrome, what other condition might I have?
  • What tests do you recommend?
  • What medications or treatments do you recommend?
  • Will I have permanent damage to my kidneys?
  • Will I have high blood pressure or other kidney problems in the future?

Additional Common Questions

What is the difference between hemolytic uremic syndrome and thrombocytopenic thrombotic purpura?

Previously, healthcare providers grouped HUS and thrombocytopenic thrombotic purpura (TTP) together. HUS and TTP are similar disorders. TTP causes blood clots to form in your small blood vessels.

Healthcare providers once referred to them as HUS/TTP because they had similar symptoms. Now, healthcare providers recognize them as separate conditions.

A note from Cleveland Clinic

Hemolytic uremic syndrome is a serious condition that affects the blood vessels in your kidneys. Most people get HUS from E. coli. The best and easiest way to avoid an E. coli infection is to regularly wash your hands with soap and water, especially after handling raw foods, before eating, after using the bathroom and after changing diapers.

If you have diarrhea for more than three days or bloody diarrhea, feel tired, look pale and don’t pee a lot when you use the bathroom, see your healthcare provider right away. The sooner you treat HUS, the less risk you have of developing lasting harm to your kidneys.

Medically Reviewed

Last reviewed on 09/06/2022.

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