Health Encyclopedia

Hemolytic-uremic syndrome

Definition

Hemolytic-uremic syndrome (HUS) is a disorder that usually occurs when an infection in the digestive system produces toxic substances that destroy red blood cells. It often affects the kidneys.

Alternative Names

HUS

Causes, incidence, and risk factors

Hemolytic-uremic syndrome (HUS) often occurs after a gastrointestinal infection with E. coli bacteria (Escherichia coli O157:H7). However, the condition has also been linked to other gastrointestinal infections, including shigella and salmonella , as well as non-gastrointestinal infections.

HUS is most common in children. It was once very rare, but it is increasing in children. It is the most common cause of acute kidney failure in children. Several large outbreaks in 1992 and 1993 were linked to undercooked hamburger meat contaminated with E. coli.

Other risk factors for HUS are unknown, although some cases are due to a familial form of the disease. HUS may occur with a variety of other diseases and infections, and after taking certain medications such as mitomycin C or ticlopidine.

HUS is more complicated in adults. It is similar to another disease called thrombotic thrombocytopenic purpura (TTP).

Symptoms

HUS often begins with vomiting and diarrhea, which may be bloody. Within a week, the person may become weak and irritable. Persons with this condition may urinate far less than normal. Urine output may almost stop.

Red blood cell destruction leads to symptoms of anemia.

Early symptoms:

Later symptoms:

Bruising
Decreased consciousness
Low urine output
No urine output
Paleness
Seizures -- rare
Skin rash that looks like fine red spots (petechiae)
Yellow skin (jaundice)

Signs and tests

The health care provider will perform a physical exam. This may show:

Liver or spleen swelling
Nervous system changes

Laboratory tests will show signs of hemolytic anemia and acute renal failure. Laboratory tests may include:

Blood clotting tests (PT and PTT)
Chem-20 may show increased levels of BUN and creatinine
Complete blood count (CBC) may show increased white blood cell count and decreased red blood cell count
Platelet count
Urinalysis may reveal blood and protein in the urine
Urine protein test can be used to show the specific amount of protein in the urine

Other tests:

Kidney biopsy
Stool culture may be positive for a certain type of E. coli bacteria or other bacteria

Treatment

Treatment may involve:

Dialysis
Medications such as corticosteroids
Transfusions of packed red cells and platelets

Some people may have the liquid portion of their blood (plasma) removed and replaced with fresh (donated) plasma, or the plasma is filtered to remove antibodies from the blood.

Expectations (prognosis)

This is a serious illness in both children and adults, and it can cause death. With proper treatment, more than half of patients will recover. The outcome is better in children than adults.

Complications

Blood clotting problems
Hemolytic anemia
Kidney failure
Nervous system problems
Too few platelets (thrombocytopenia)
Uremia

Calling your health care provider

Call your health care provider if you develop symptoms of HUS. Emergency symptoms include:

Blood in the stool
No urination
Reduced alertness (consciousness)

Call your health care provider if you have had an episode of HUS and your urine output decreases, or you develop other new symptoms.

Prevention

You can prevent the known cause, E. coli, by cooking hamburger and ground meats well and avoiding contact with unclean water.

References

McMillan R. Hemorrhagic disorders: abnormalities of platelet and vascular function. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 179.

Review Date:11/10/2008
Reviewed By:David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and James R. Mason, MD, Oncologist, Director, Blood and Marrow Transplantation Program and Stem Cell Processing Lab, Scripps Clinic, Torrey Pines, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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