Hemolytic Uremic Syndrome

What is hemolytic uremic syndrome?

Hemolytic uremic syndrome (hee-mah-lit-ick yer-ee-mik sin-drohm) is a 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) in your blood.

Hemolytic uremic syndrome (HUS) can affect anyone. But you’re more likely to get it from a bacterial infection that causes loose poop (diarrhea), especially Escherichia coli (E. coli). However, a syndrome is a group of symptoms that may have different causes. So,even though you’re more likely to get HUS from E. coli, you could get it from something else.

HUS can affect other organs in your body, including your heart and brain. But it most commonly affects your kidneys.

Contact a healthcare provider if you have bloody diarrhea or diarrhea that lasts longer than three days. Without treatment, a severe case of HUS can be deadly.

What are the different types of hemolytic uremic syndrome?

Types of hemolytic uremic syndrome include:

• “Typical” hemolytic uremic syndrome. This is the most common type. You’re more likely to get hemolytic uremic syndrome from a bacterial infection that affects your small intestine and large intestine (collectively your bowels).
• Atypical hemolytic uremic syndrome (aHUS). You inherit aHUS from a biological parent.
• Secondary hemolytic uremic syndrome. Secondary HUS coexists with other conditions.

What is atypical hemolytic uremic syndrome?

Atypical hemolytic uremic syndrome (aHUS) is a rare type of HUS. Common symptoms include:

• Low levels of red blood cells.
• Low platelet count.
• Sudden (acute) kidney failure.
• High blood pressure (hypertension) or worsening control of your blood pressure.

Atypical hemolytic uremic syndrome is usually a genetic disorder. That means biological parents pass it down to their children. Genetic mutations in some of your genes that encode proteins can cause aHUS. An illness, infection or an environmental factor triggers the mutation to activate.

How common is hemolytic uremic syndrome?

Hemolytic uremic syndrome affects between 5% and 15% of people who have E. coli diarrhea. aHUS is very rare, occurring in less than 1 person in 1 million people.

What are the most common symptoms of hemolytic uremic syndrome?

The most common symptoms of hemolytic uremic syndrome include:

• Diarrhea, usually bloody.
• Abdominal pain.
• Nausea and vomiting.
• Headache.
• Chills and fever.

Other common symptoms may include:

• Easy bruising.
• Pale skin (pallor), or the linings of your nose and mouth (mucosa) are pale.
• Confusion.
• Seizure.
• Stroke.
• Rapid heart rate (arrhythmia).

In severe cases of HUS, damaged red blood cells can cause blood clots that damage your organs, especially your kidneys. This affects how well your kidneys can filter and eliminate waste from your body. If your kidneys can’t filter and eliminate waste, it can lead to acute kidney injury (AKI). AKI symptoms include:

• Blood in your pee (hematuria).
• Increased blood toxin levels, which can make you feel generally sick.
• High blood pressure.
• Shortness of breath (dyspnea).
• Swelling (edema), especially in your legs, feet or ankles.
• Peeing less than expected (oliguria).

What causes hemolytic uremic syndrome?

Certain strains of the bacteria E. coli cause most cases of hemolytic uremic syndrome. These strains produce the toxin Shiga. Shiga damages the lining of your small intestine and causes diarrhea. It can also enter your bloodstream, destroy red blood cells and damage your kidneys. You’re more likely to get an E. coli infection when you eat spoiled, undercooked or poorly processed foods or drinks, such as:

• Undercooked meat (usually ground beef).
• Unpasteurized milk (raw milk) or fruit juice. Pasteurization is a mild heating process that kills harmful pathogens like bacteria.
• Unwashed and contaminated raw fruits and vegetables.

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.

In rare cases, certain medications and substances may cause secondary HUS as a side effect. These may include:

• Chemotherapy drugs, including bleomycin, cisplatin, carfilzomib, gemcitabine and mitomycin.
• Immunosuppressant drugs, including cyclosporine, tacrolimus, muromonab-CD3 (OKT3) and interferons.
• Quinine, which treats malaria.
• Some drugs of abuse such as oxymorphone, ecstasy and cocaine.

Is hemolytic uremic syndrome contagious?

No, hemolytic uremic syndrome isn’t contagious. You can’t get HUS from person-to-person contact.

But E. coli is contagious. You can get it after consuming contaminated foods or drinks or coming into contact with a contaminated person’s or animal’s poop.

Who does hemolytic uremic syndrome affect?

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

• Are younger than 5 years old.
• Have a weakened immune system (immunocompromised).
• Have a biological family history of HUS.
• Get an E. coli infection, usually from eating undercooked meat or drinking unpasteurized (raw) dairy milk.
• Come into direct contact with someone who has diarrhea from an E. coli infection.

How is hemolytic uremic syndrome diagnosed?

A healthcare provider will diagnose hemolytic uremic syndrome by:

• Reviewing your medical history.
• Asking about your family medical history.
• Conducting a physical examination.

If they suspect you have HUS, they’ll also order tests.

What tests will be done to diagnose hemolytic uremic syndrome?

A healthcare provider may order the following tests to diagnose hemolytic uremic syndrome:

• Pee test (urinalysis). You’ll pee into a special container and a provider will examine it to see if you have protein or blood in your pee.
• Blood test. A provider will use a small needle to withdraw a sample of blood from a vein, usually in your arm.
• Stool (poop) test. A provider will give you a special container. The next time you have to poop, you’ll collect it in the container and return it to the provider.
• Genetic testing. A provider may send part of your blood sample to a lab for genetic testing. Genetic testing helps determine if you’re more likely to get HUS because of your genes (genetic tendency). It also helps the provider decide which treatment you may need.
• Kidney biopsy. A provider will remove a small part of your kidney and examine it under a microscope to see how well your kidneys work.

Which findings indicate hemolytic uremic syndrome?

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

• Pee tests look for blood or protein.
• Blood tests detail your red blood cell levels and platelet levels. They can also show how well your kidneys and liver work.
• Stool tests check for the presence of E. coli O157 and other bacteria that may cause HUS.
• A kidney biopsy shows damage to your kidney and sometimes the cause of the damage.

How is hemolytic uremic syndrome treated?

You must get hemolytic uremic syndrome treatment at a hospital. Treatment may include:

• Intravenous (IV) fluids and/or tube feeding. IV fluids help keep you hydrated. Tube feeding (enteral nutrition) ensures you’re getting nutrients.
• Medications. Blood pressure medications (antihypertensives) help reduce your blood pressure and reduce kidney damage. A provider may prescribe eculizumab or ravulizumab if you have atypical hemolytic uremic syndrome. Eculizumab and ravulizumab increase your chances of developing meningococcal disease and pneumococcal disease. A provider will prescribe meningococcal and pneumococcal vaccinations before you start eculizumab or ravulizumab. You may also need antibiotics for at least two weeks.
• Blood transfusions. It’s important that you get red blood cells and platelets if you have HUS. Red blood cells help with symptoms of anemia, including shortness of breath and rapid heart rate. Platelets help your blood clot, especially if you’re bleeding or bruising easily.

If you have severe kidney damage, you may need dialysis to clean your blood while your kidneys heal. If HUS causes kidney failure, you may need a kidney transplant.

Can you recover from hemolytic uremic syndrome?

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

About 20% to 50% of children have mild chronic kidney disease (CKD) and 3% to 5% develop kidney failure (end-stage kidney disease). In adults, research estimates about 45% had CKD.

More than 85% of people with HUS recover complete kidney function. But, even if you make a full recovery, you may have high blood pressure or other kidney problems in the future.

Can hemolytic uremic syndrome be prevented?

You can help prevent an E. coli infection that causes hemolytic uremic syndrome by:

• Avoiding unsanitary swimming areas, such as lakes or rivers that have high levels of bacteria in the water.
• Avoiding swimming if you have diarrhea.
• Avoiding drinking unpasteurized (raw) drinks, including milk, cider and juice.
• Cleaning kitchen utensils (like knives, forks, spatulas, tongs and spoons) and food surfaces (including countertops, cutting boards and plates) regularly.
• Cooking eggs and ground meats to an internal temperature of at least 160 degrees Fahrenheit (71 degrees Celsius) and poultry to an internal temperature of at least 165 degrees Fahrenheit (74 degrees Celsius).
• Defrosting meat in the microwave or refrigerator, not on a food surface or in warm water.
• Separating raw foods from cooked foods.
• Washing your hands with soap and warm water before eating and after using the restroom, changing diapers and touching farm animals.

What can I expect if I have hemolytic uremic syndrome?

With proper diagnosis and care, many people with HUS make a full recovery without any permanent damage to their health. But you have an increased chance of developing high blood pressure or other conditions that may affect your kidneys in the future.

Severe cases of HUS can be fatal without treatment, especially if HUS affects other organs like your brain.

What is the survival rate for hemolytic uremic syndrome?

With proper diagnosis and treatment, more than 90% of people survive hemolytic uremic syndrome.

How do I take care of myself?

If you or your child has severe diarrhea, it’s important to try to rehydrate. Rehydration drinks help replace lost electrolytes. Babies and younger children may need breast (chest) milk or formula to rehydrate. Call a healthcare provider to help you determine the best way to keep your child hydrated

When should I see a healthcare provider?

Contact a healthcare provider if you have:

• Bloody diarrhea.
• Diarrhea that lasts longer than three days.
• Swelling.
• Easily bruised skin.
• Fatigue.

Which questions should I ask a healthcare provider?

Questions you may want to ask a healthcare provider include:

• How will you confirm 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?
• Which 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?

What is the triad of hemolytic uremic syndrome?

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

The hemolytic uremic syndrome triad includes:

• Damage to your red blood cells (microangiopathic hemolytic anemia).
• A steady decrease in the number of platelets in your blood (thrombocytopenia).
• Acute kidney injury.

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

If you have diarrhea, it doesn’t mean you have hemolytic uremic syndrome. But see a healthcare provider if you have bloody diarrhea or severe diarrhea in which you can’t stay hydrated or it lasts longer than three days.

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

Hemolytic uremic syndrome and thrombotic thrombocytopenic purpura (TTP) are similar disorders — TTP also causes blood clots to form in your small blood vessels. Previously, healthcare providers grouped HUS and TTP together. But they now recognize them as separate conditions.

A note from Cleveland Clinic

Diarrhea is usually a short-term, but uncomfortable and annoying, condition that gets better after a day or two. But if you have bloody diarrhea or diarrhea that lasts for longer than three days and you feel tired, look pale and don’t pee a lot when you use the bathroom, it’s time to see a healthcare provider. Hemolytic uremic syndrome can severely damage your kidneys and affect other organs. The sooner you treat it, the less risk you have of developing lasting harm to your kidneys.