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Hemolytic uremic syndrome (HUS)By Mayo Clinic staff
Original Article: http://www.mayoclinic.com/health/hemolytic-uremic-syndrome/DS00876
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 several 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 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:
- Bloody diarrhea
- Abdominal pain
- Pale skin tone
- Fatigue and irritability
- Fever, usually not high
- 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
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.
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.
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), anti-platelet medications and oral contraceptives
- Certain infections, such as HIV/AIDS or an infection with the pneumococcal bacteria
However, the cause of hemolytic uremic syndrome in adults is often unknown.
Those most at risk of developing hemolytic uremic syndrome are:
- Children under 5 years of age
- People who have weakened immune systems
- Adults older than 60 years of age
- People who have certain genetic changes that make them more susceptible
Hemolytic uremic syndrome can cause a number of serious, life-threatening complications, including:
- Sudden (acute) kidney failure
- High blood pressure
- Chronic kidney failure
- Heart problems
Preparing for your appointment
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 doctors, 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 your or your child's diarrhea?
- What other signs and symptoms — such as fever, swelling or decreased urine output — 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?
Tests and diagnosis
If your doctor suspects hemolytic uremic syndrome, various lab tests may be done to confirm the diagnosis.
- Blood tests. 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. A blood sample can also be used to determine if your red blood cells are damaged.
- Urine test. Your doctor may also collect a urine sample to test for blood in your urine.
- Stool sample. Additionally, your doctor may take a stool sample to test for the presence of bacteria.
Treatments and drugs
Hemolytic uremic syndrome requires treatment in the hospital. To ease immediate signs and symptoms and prevent further problems, hemolytic uremic syndrome treatment may include:
- Fluid replacement. Lost fluid and electrolytes need to be carefully replaced because the kidneys aren't removing fluids and waste as efficiently as normal.
- 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 clot more normally. 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. This process is called plasmapheresis.
- 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 take precautions against E. coli, and other foodborne illnesses. It's important to note that meat or produce contaminated with E. coli won't necessarily look, feel or smell bad. Things you can do that will help reduce your risk of foodborne illness:
- 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) throughout. Check the temperature of the meat with a thermometer.
- Wash fruits and vegetables under running water.
- Avoid unpasteurized milk, juice and cider.
- Avoid swimming in water potentially contaminated with feces, and don't swim if you have diarrhea.
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.
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