Hemolytic Uremic Syndrome (HUS)
Kidney injury from red blood cell destruction and tiny clots
Quick Facts
- Type: Serious blood and kidney disorder
- Common trigger: Certain E. coli infections
- Most affected: Young children
- Urgency: Medical emergency — needs hospital care
Overview
Hemolytic uremic syndrome (HUS) is a serious condition in which red blood cells are destroyed and tiny clots form in small blood vessels, particularly in the kidneys. This combination leads to anemia, a low platelet count, and kidney injury. HUS is a leading cause of sudden kidney failure in young children.
The most common form follows an intestinal infection with certain strains of E. coli bacteria that produce a toxin, often after eating contaminated food. A rarer form, sometimes called atypical HUS, is caused by problems in the immune system's complement pathway. HUS requires hospital care, and with prompt treatment many children recover well, though some develop lasting kidney problems.
Symptoms
HUS often follows a few days of diarrhea, which may be bloody. As the syndrome develops, symptoms include:
- Decreased urination or dark, tea-colored urine
- Unusual tiredness, weakness, and paleness from anemia
- Easy bruising or tiny red spots on the skin
- Swelling of the face, hands, feet, or whole body
- Irritability, confusion, or in severe cases seizures
- High blood pressure
- Reduced alertness
Seek urgent medical care for a child with bloody diarrhea, much less urine than usual, extreme tiredness, paleness, swelling, or confusion. These can be signs of HUS and kidney injury.
Causes
HUS occurs when small blood vessels are damaged, leading to clots that destroy red blood cells and harm the kidneys. The main causes are:
- Shiga toxin-producing E. coli: The most common cause, especially a strain known as E. coli O157:H7. Infection usually comes from undercooked ground beef, unpasteurized milk or juice, contaminated produce or water, or contact with infected animals or people.
- Other infections: Certain other bacteria can also trigger HUS.
- Atypical HUS: A rarer form caused by inherited or acquired problems in the complement immune system, not by infection.
Risk Factors
- Young age, especially children under 5
- Recent infection with Shiga toxin-producing E. coli
- Eating undercooked meat or unpasteurized dairy or juice
- Contact with contaminated water, such as some lakes or pools
- A family history of atypical HUS
- Older adults can also be affected
Diagnosis
Doctors diagnose HUS using blood and urine tests, often in a child who has recently had diarrhea.
- Complete blood count: Shows anemia and a low platelet count.
- Blood smear: Reveals fragmented red blood cells.
- Kidney function tests: Blood tests and urine tests show reduced kidney function and protein or blood in the urine.
- Stool testing: To detect E. coli or its toxin.
Additional tests may be done if an atypical, non-infectious form is suspected.
Treatment
HUS is treated in the hospital with supportive care while the kidneys recover. There is no medicine that cures the typical, infection-related form, so care focuses on protecting the body's organs.
- Fluid and electrolyte management: Careful balancing of fluids and minerals.
- Blood transfusions: Red blood cells for severe anemia and platelets if needed.
- Dialysis: Temporary kidney support if the kidneys are failing.
- Blood pressure control: Medications to manage high blood pressure.
- Targeted therapy for atypical HUS: Specific complement-blocking treatment is used for that form.
Antibiotics are generally not recommended for E. coli-related HUS, as they may worsen the illness in some cases.
Prevention
Most HUS can be prevented by avoiding the infections that trigger it:
- Cook ground beef thoroughly until no pink remains
- Avoid unpasteurized milk, juice, and cider
- Wash fruits and vegetables well
- Wash hands carefully after using the bathroom, before eating, and after contact with animals
- Avoid swallowing water from lakes, pools, or untreated sources
- Keep raw meat separate from other foods to prevent cross-contamination
When to See a Doctor
Seek urgent medical care if a child has bloody diarrhea, or if anyone with recent diarrhea develops much less urine than usual, marked paleness, extreme tiredness, swelling, unexplained bruising, or confusion. These may be early signs of HUS.
Go to the emergency department for severe symptoms such as no urine output, seizures, or decreased alertness, which need immediate treatment.
Frequently Asked Questions
What causes hemolytic uremic syndrome?
The most common cause is infection with certain Shiga toxin-producing E. coli bacteria, often from undercooked beef, unpasteurized dairy or juice, contaminated produce, or contact with infected animals or people. A rarer form, atypical HUS, is caused by problems in the immune system rather than infection.
Is HUS a medical emergency?
Yes. HUS can cause sudden kidney failure and other serious complications, so it needs hospital care. A child with bloody diarrhea, very little urine, marked paleness, swelling, or confusion should be evaluated urgently.
Why are antibiotics usually avoided in HUS?
For the common E. coli-related form, antibiotics are generally not recommended because they may increase the release of the toxin and worsen the illness in some cases. Treatment focuses on supportive care while the kidneys recover.
Do children recover from HUS?
Many children recover well with prompt hospital treatment, and kidney function often returns. However, some develop lasting kidney problems or high blood pressure, so follow-up care is important after recovery.
How can HUS be prevented?
Most cases can be prevented by avoiding the triggering infections: cook ground beef thoroughly, avoid unpasteurized milk and juice, wash produce, wash hands carefully, and avoid swallowing untreated water. Preventing E. coli infection is the key step.
References
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Hemolytic Uremic Syndrome in Children.
- Centers for Disease Control and Prevention (CDC). E. coli (Escherichia coli).
- MedlinePlus, U.S. National Library of Medicine. Hemolytic-uremic syndrome.
- Mayo Clinic. Hemolytic uremic syndrome (HUS).