Hemolytic-uremic syndrome

Also known as: HUS

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, causing kidney injury.

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 nongastrointestinal infections.

HUS is most common 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 less than normal. Urine output may almost stop.

Red blood cell destruction leads to symptoms of anemia.

Early symptoms:

• Blood in the stools
• Irritability
• Fever
• Lethargy
• Vomiting and diarrhea
• Weakness

Later symptoms:

• Bruising
• Decreased consciousness
• Low urine output
• No urine output
• Pallor
• 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)
• Comprehensive metabolic panel 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 is usually reduced
• Urinalysis may reveal blood and protein in the urine
• Urine protein test can be used to show the 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 blood 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 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.

See also:

• Disease

  Thrombocytopenia

  Thrombocytopenia is any disorder in which there is an abnormally low amount of platelets. Platelets are parts of the blood that help blood to clot. This condition is sometimes associated with abnormal bleeding.

• Disease

  Thrombotic thrombocytopenic purpura

  

  Thrombotic thrombocytopenic purpura (TTP) is a blood disorder that causes blood clots to form in small blood vessels around the body, and leads to a low platelet count (). See also:

• Disease

  Acute kidney failure

  

  Acute (sudden) kidney failure is the sudden loss of the ability of the kidneys to remove waste and concentrate urine without losing .

• Symptoms

  Paleness

  

  Paleness is an abnormal loss of color from normal skin or .

• Disease

  Anemia

  

  Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues. See also:

• Disease

  Chronic kidney disease

  

  Chronic kidney disease is the slow loss of kidney function over time. The main function of the kidneys is to remove wastes and excess water from the body.

• Special Topic

  Hemolysis

  Hemolysis is the breakdown of red blood cells. See also:

• Disease

  Prerenal azotemia

  

  Prerenal azotemia is an abnormally high level of nitrogen-type wastes in the blood.

• Disease

  Hemolytic anemia

  

  Hemolytic is a condition in which there are not enough red blood cells in the blood, due to the premature destruction of red blood cells. There are a number of specific types of hemolytic anemia, which are described individually.

Review date:

March 28, 2010

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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