What Is Hemolytic Uremic Syndrome?

Hemolytic uremic syndrome (HUS) is a complex condition where an immune reaction, most commonly after a gastrointestinal tract infection, causes low red blood cell levels, low platelet levels, and kidney injury.

Infections of the gastrointestinal tract (your stomach and intestines) are the most common cause of this syndrome. The body’s immune system reacts to toxins released during an intestinal bacterial infection. This causes damage and destruction to blood cells as they circulate through the blood vessels. These include red blood cells (RBC) and platelets, causing them to die prematurely. The kidney is affected in two ways.The immune reaction can cause direct damage to kidney cells resulting in kidney injury. Alternatively, a build-up of destroyed RBCs or platelets can clog up the kidney’s filtering system and cause kidney injury or a build-up of waste products in the body, since the kidney can no longer efficiently eliminate waste from the blood.

Kidney injury can be quite serious if left untreated. Kidney failure, dangerous elevations in blood pressure, heart problems, and stroke are all concerns if HUS advances without prompt treatment.

HUS is the most common cause of acute kidney failure in children. It is most common in children under the age of 5, although older children and adults can also suffer from the disorder.

Fortunately, most people who receive prompt treatment can make a full recovery without permanent kidney damage.

Recognizing Symptoms of Hemolytic Uremic Syndrome

The symptoms of HUS vary. Symptoms could include:

  • bloody diarrhea
  • abdominal pain
  • pale skin
  • irritability
  • fatigue
  • fever
  • unexplained bruises or bleeding
  • decreased urination
  • abdominal swelling
  • blood in the urine
  • confusion
  • vomiting
  • swollen face
  • swollen limbs
  • seizures (uncommon)

What Causes Hemolytic Uremic Syndrome?

HUS occurs where an immune reaction causes destruction to blood cells. This results in low red blood cell levels, low platelet levels, and kidney injury

HUS in Children

The most common underlying cause of HUS in children is infection with Escherichia Coli (E. coli). There are many different forms of E. coli, and most do not cause problems. In fact, E. coli bacteria are normally found in the intestines of healthy people and animals. However, some specific strains of E. coli, passed on through contaminated food, are responsible for infections that can lead to HUS. Bodies of water that are contaminated with feces may also carry E. coli.

Other bacteria such as Shigella dysenteriae and Salmonella typhi can cause HUS.

HUS in Adults

HUS in adults can also be triggered by infection with E. coli.. There are also many non-bacterial causes of HUS in adults that are less common, including:

  • pregnancy
  • HIV/AIDS infection
  • quinine (used for muscle cramps)
  • chemotherapy and immunosuppressant medication
  • birth control pills
  • anti-platelet medications
  • cancer
  • systemic lupus and glomerulonephritis

Diagnosing Hemolytic Uremic Syndrome

Some very basic tests can be ordered to determine whether blood cells have been damaged or kidney function compromised:


A complete blood count (CBC) measures the quantity and quality of RBCs and platelets in a blood sample.

Other Blood Tests

In order to test for loss of kidney function, your doctor may order a BUN test (which looks for elevated urea by-products) and creatinine test (looking for elevated muscle by-products). Abnormal results could indicate kidney problems.

Urine Test

Your doctor will want to test for blood or protein in your urine.

Stool Sample

Bacteria or blood in your stool could help your doctor isolate the underlying cause of your symptoms.

How Is Hemolytic Uremic Syndrome Treated?

Common treatments for HUS may include:

Fluid Replacement

The key treatment for HUS is fluid replacement. This treatment replaces electrolytes that the body needs to function. Electrolytes are minerals such as calcium, potassium, and magnesium. Fluid replacement also increases blood flow through the kidneys.. Your doctor will give you intravenous fluids, but may also encourage you to boost your fluid intake by drinking more water or electrolyte solutions.

Blood Transfusion

A red blood transfusion may be necessary if you have a low level of RBCs. Transfusions are performed in the hospital. Transfusions can relieve symptoms associated with low RBC counts, such as shortness of breath and extreme fatigue.

These symptoms are consistent with anemia, a condition in which your body cannot produce enough red blood cells to supply the body organs with sufficient oxygen to carry on normal metabolism. This caused by the loss of RBC’s.

Other Treatments

Your doctor will take you off of any medications that could be the underlying cause of HUS.

Platelet transfusion may be necessary if you have a low platelet count.

Plasma exchange is another form of treatment, in which your doctor replaces your blood plasma with plasma from a donor. You will receive healthy plasma to support the circulation of healthy, new red blood cells and platelets.

What Are Possible Complications for Hemolytic Uremic Syndrome?

In extreme cases if your kidneys have failed, kidney dialysis may be used to filter waste from your body. This is a temporary treatment until the kidneys can function normally. If they do not regain normal function, you may need a kidney transplant.

Long-Term Complications

The main complication of HUS is kidney failure. However, HUS can also cause:

  • high blood pressure
  • pancreatitis
  • altered mental state
  • seizures
  • cardiomyopathy
  • stroke
  • coma

Fortunately, most people are able to make a full recovery from HUS.

What Is the Outlook for Hemolytic Uremic Syndrome?

HUS is potentially a very serious condition. However, you are likely to make a full recovery if you are diagnosed in the early stages of the condition and start treatment right away. Call your doctor anytime you develop symptoms that you are concerned about.

How Can You Prevent Hemolytic Uremic Syndrome?

The most common cause of HUS is infections by E. coli. Although you cannot avoid these bacteria entirely, you can reduce your risk of infection by:

  • washing your hands regularly
  • thoroughly washing utensils
  • keeping food preparation surfaces clean
  • keeping raw food separate from ready-to-eat food
  • defrosting meat in the refrigerator instead of on the counter
  • not leaving meat at room temperature (this can cause bacterial growth).
  • cooking meat to 160 degrees Fahrenheit to kill harmful bacteria
  • washing fruits and vegetables thoroughly
  • not swimming in contaminated water
  • avoiding ingestion of unpasteurized juice or milk