Hemolytic uremic syndrome (HUS) 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 HUS advances without prompt treatment.
HUS 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 HUS will experience some degree of kidney failure (NKUDIC). However, with treatment, most patients can make a full recovery without permanent kidney damage.
HUS occurs when bacterial toxins begin to damage the lining of blood vessels, resulting in the destruction of red blood cells and platelets.
HUS in Children
The most common underling 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.
HUS in Adults
While HUS 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 HUS in adults, including:
- HIV/AIDS infection
- quinine (used for muscle cramps)
- chemotherapy and immunosuppressant medication
- birth control pills
- anti-platelet medications
- systemic lupus and glomerulonephritis
The symptoms of HUS 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
- unexplained bruises or bleeding
- decreased urination
- abdominal swelling
- blood in the urine
- swollen face
- swollen limbs
- seizures (extreme cases)
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.
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.
Your doctor will want to test for blood and/or protein in your urine.
Bacteria or blood in your stool could help your doctor isolate the underlying cause of your symptoms.
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. The extra fluids help offset the impaired blood flow that occurs due to the breakdown of red blood cells. Your doctor will give you intravenous fluids, but may also encourage you to boost your fluid intake by drinking more water or electrolyte solutions.
A red blood transfusion may be necessary if you have a low level of RBCs. Transfusion would be 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.
Platelet transfusion may be necessary if you have a low platelet count.
Plasma exchange is another form of treatment, in which your blood plasma is replaced with plasma from a donor. You will receive healthy plasma to support the circulation of healthy, new red blood cells and platelets.
If your kidneys have failed, kidney dialysis may be used to filter waste from the 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.
The main complication of HUS is kidney failure. However, HUS can also cause:
- high blood pressure
- altered mental state
According to an article published in American Family Physician, approximately 12 percent of patients with HUS either develop end-stage renal disease or die (Razzaq, 2006). Most of the remaining patients will recover fully.
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