Hemolytic Uremic Syndrome Causes, Symptoms, Diagnosis, Treatment, Prevention

Hemolytic Uremic Syndrome Causes, Symptoms, Diagnosis, Treatment, Prevention

What is Hemolytic Uremic Syndrome?

Hemolytic uremic syndrome is a complex condition in which a buildup of broken-down blood cells leads to serious kidney damage.

Infections of the gastrointestinal tract (your stomach and intestines) are the most common cause of this disorder. Toxins released during an intestinal bacterial infection can destroy the lining of small blood vessels in your stomach or intestines. This, in turn, causes damage and destruction to blood cells as they circulate through the blood vessels. This destruction affects red blood cells (RBC) and platelets, causing them to die prematurely. A buildup of these destroyed cells clogs the kidneys’ filtering system, reducing the blood flow to the kidneys. Your kidneys are responsible for filtering out waste products and toxins so they can be eliminated from your body.

The damage to your health and kidney function can be quite serious if left untreated, or if complications arise. Kidney failure, high blood pressure, heart problems, and stroke are all concerns if Hemolytic Uremic Syndrome advances without prompt treatment.

Hemolytic Uremic Syndrome is the most common cause of kidney failure in children. It is most common in children under the age of 10, although older children and adults can also suffer from the disorder.

According to the National Kidney and Urologic Diseases Information Clearinghouse, more than half of children with Hemolytic Uremic Syndrome will experience some degree of kidney failure (NKUDIC). However, with treatment, most patients can make a full recovery without permanent kidney damage.

What Causes Hemolytic Uremic Syndrome?

Hemolytic Uremic Syndrome occurs when bacterial toxins begin to damage the lining of blood vessels, resulting in the destruction of red blood cells and platelets.

Hemolytic Uremic Syndrome in Children

The most common underling cause of Hemolytic Uremic Syndrome 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 Hemolytic Uremic Syndrome. Bodies of water that are contaminated with feces may also carry E. coli.

Other bacteria such as Shigella dysenteriae and Salmonella typhi can cause Hemolytic Uremic Syndrome.

Hemolytic Uremic Syndrome in Adults

While Hemolytic Uremic Syndrome in adults can also be triggered by infection with E. coli, the mechanisms that lead to the destruction of blood cells are more complicated than in children. There are also many non-bacterial causes of Hemolytic Uremic Syndrome in adults, 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

Recognizing Symptoms of Hemolytic Uremic Syndrome

The symptoms of Hemolytic Uremic Syndrome vary. They can result from E. coli toxins, kidney damage, and the loss of red blood cells and platelets. 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 (extreme cases)

Medical Emergencies

Any of these symptoms should be investigated by a physician. However, blood in the urine or stool and unexplained swelling in any part of the body are medical emergencies. If these occur, seek medical attention immediately.

How is hemolytic uremic syndrome diagnosed?

The health care professional will have a suspicion of the disease based on the history and physical examination, especially in a small child who has had the typical bloody diarrhea. Abnormal laboratory tests help confirm the diagnosis. These abnormal findings may include:

Hemolytic anemia

The red blood cell count is low and a peripheral blood smear, in which blood is examined under a microscope, will show that the red cells have been damaged and destroyed. This differentiates hemolysis (hemo=blood + lysis=destruction) from anemia caused by decreased production of blood cells in the bone marrow.


a low platelet count


Kidney function can be measured by testing the level of waste products in the blood normally filtered by the kidney. BUN (blood urea nitrogen) and creatinine are measures of this kidney function. When levels rise, it is an indication of kidney failure or uremia in which the kidneys cannot clear the waste products of metabolism from the body.

Abnormal urine findings

Blood and protein may be found in the urine when normally they are not present.

Stool cultures

Since E. coli O157:O7 is the most common cause of Hemolytic Uremic Syndrome in children; attempts are made to culture the bacteria from stool samples. The body usually clears the bacteria from the stool within a week, so a negative test does not exclude the disease. A positive test helps confirm Hemolytic Uremic Syndrome and will be reported to public health authorities to try to determine the source of the infection. In 2011, outbreaks in Europe were traced by public health authorities to tainted sprouts.

In atypical Hemolytic Uremic Syndrome, history is very important to search for other potential causes of the disease. Unfortunately, the case may not be found in up to half of cases of atypical Hemolytic Uremic Syndrome.

One of the distinguishing findings between Hemolytic Uremic Syndrome and TTP is a normal neurologic examination. The brain function is normal in Hemolytic Uremic Syndrome.

What is the treatment for hemolytic uremic syndrome?

Typical Hemolytic Uremic Syndrome in children tends to be self-limiting, and supportive care is often all that is needed. This may include intravenous fluids for rehydration and rebalancing of electrolytes like sodium and potassium, which can be lost with the diarrhea.

Blood transfusions are only used for the most severe cases of anemia in which the hemoglobin falls below 6 or 7 g/dL (depending on age, the normal value is 11-16).

Kidney failure may be managed expectantly (by observation and supportive care), and dialysis is not often required.

Adults with atypical Hemolytic Uremic Syndrome tend to become more ill and need more aggressive therapy than children with the condition. In addition to the supportive care discussed above, plasmapheresis or plasma exchange may be required. Since it is thought there is an abnormal chemical in the plasma stimulating the abnormal clot formation, removing the plasma and replacing it with donor plasma is helpful in treating adult Hemolytic Uremic Syndrome.

Dialysis may be needed while awaiting recovery of the kidneys from the illness.

Eculizumab (Soliris) has been approved by the FDA for the treatment of atypical Hemolytic Uremic Syndrome. It is a monoclonal antibody that decreases the blood clotting in the capillary blood vessels, decreasing the potential destruction of cells. This type of therapy decreases the body's immune capabilities, and the risk of infection increases.

How can hemolytic uremic syndrome be prevented?

Most cases of typical Hemolytic Uremic Syndrome associated with diarrhea can be prevented by thorough washing and cooking of food products. The vast majority of cases of typical Hemolytic Uremic Syndrome are caused by poor food handling from the farmer to the wholesaler and grocer. Proper washing and cooking techniques in the kitchen is the key to prevention.

Unfortunately, there is no way to prevent atypical Hemolytic Uremic Syndrome.