Hemolytic Uremic Syndrome

What is hemolytic uremic syndrome?

Hemolytic uremic syndrome (HUS) is a condition that affects the blood and blood vessels. It results in the destruction of blood platelets (cells involved in clotting), a low red blood cell count (anemia) and kidney failure due to damage to the very small blood vessels of the kidneys. Other organs, such as the brain or heart, may also be affected by damage to very small blood vessels.

Are there different types of HUS?

Yes. HUS is considered a syndrome because it is a combination of findings that may have different causes. In most cases, HUS occurs after a severe bowel infection with certain toxic strains of the bacteria called E. coli. It may also occur in response to certain medicines, but this is rare. Even more rarely, HUS occurs for unknown reasons. This fact sheet primarily focuses on the type of HUS that occurs in infants and children as a result of an E. coli infection.

What are the symptoms of HUS?

HUS generally occurs in children who have had an illness involving diarrhea (usually bloody). Most children fully recover from their bowel illness without developing HUS. However, a small percentage will become pale and have less energy, due to the progression to HUS. Their urine output may also decrease, but a loss of color in the skin is the most striking symptom.

How does HUS start?

HUS from E. coli infections results when bacterial toxins cross from the intestines into the bloodstream and damage the very small blood vessels. The toxic E. coli may come from eating spoiled, undercooked or poorly processed food products, or from exposure to contaminated water. HUS occurs most often in certain regions, such as the Pacific Northwest and Argentina.

How does HUS affect the kidneys?

In HUS the tiny filter units in the kidneys known as glomeruli become clogged with platelets and damaged red blood cells. This leads to problems with the kidney's ability to filter and eliminate waste products.

How is HUS treated?

HUS is generally treated with medical care in the hospital. Close attention to fluid volume is very important. This potentially includes intravenous (IV) fluids and nutritional supplementation by IV or tube feeding. A transfusion of blood may also be needed. In about 50 percent of cases, short-term kidney replacement treatment in the form of dialysis is necessary. Most patients who need dialysis will recover kidney function and ultimately be able to discontinue dialysis treatment. At times a special form of treatment called plasmapheresis may also be necessary.

What happens if kidney failure occurs?

When HUS causes mild kidney failure, close attention to the patient, especially to fluid volume, may be all that is necessary for adequate treatment. When it causes severe kidney failure (when kidney function is less than 10 percent of normal), dialysis may be needed to do the work of the kidneys. Different forms of dialysis may be used depending on each individual's needs. Most HUS patients that require dialysis ultimately recover their kidney function.

What are the chances of recovery from HUS?

More than 85 percent of patients with the most common form of HUS recover complete kidney function. However, even with full recovery, there is the chance for high blood pressure or other kidney problems in the years ahead. In general, the outlook in HUS is related to the severity of involvement of other organs such as the brain, pancreas, liver or heart.

If one child in a family has had HUS, are others likely to get it?

Because the most common form of HUS is due to a bowel infection, it is possible for other family members or close personal contacts to acquire the infection and develop HUS.

What is the outlook for HUS?

Although there is still much to do, there has been a significant increase in understanding the underlying cause of HUS and the processes that contribute to kidney damage. Medications that are designed to prevent the absorption of the E. coli bacterial toxins in children with HUS are currently being studied in clinical treatment trials.

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©2014 National Kidney Foundation. All rights reserved. This material does not constitute medical advice. It is intended for informational purposes only. Please consult a physician for specific treatment recommendations.