Hemolytic Uremic Syndrome (HUS)

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)
• kidney failure due to damage to the tiny blood vessels of the kidneys

Other organs, such as the brain or heart, may also be affected by damage to very small blood vessels.

Yes. HUS is considered a syndrome because it 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 article primarily focuses on the type of HUS that occurs in infants and children due to an E. coli infection.

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 become pale and have less energy due to HUS progression. Their urine output may also decrease, but a loss of color in the skin is the most striking symptom.

HUS from E. coli infections results when bacterial toxins cross the intestines into the bloodstream and damage the tiny blood vessels. Common causes of the toxic E. coli may come from:

• spoiled food
• undercooked foods
• poorly processed food products
• exposure to contaminated water

HUS occurs most often in certain regions, such as the Pacific Northwest and Argentina.

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.

HUS is generally treated with medical care in the hospital. Fluid volume management is crucial and may include:

• intravenous (IV) fluids
• nutritional supplementation by IV or tube feeding
• blood transfusions 

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 discontinue dialysis treatment. At times a special form of treatment called plasmapheresis may also be required.

When HUS causes mild kidney failure, fluid volume management 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.

Learn about dialysis.

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.

Because the most common form of HUS is due to a bowel infection, other family members or close personal contacts can acquire the infection and develop 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 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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© 2015 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.