HEMOLYTIC-UREMIC SYNDROME

Hemolytic-Uremic Syndrome is most common in children. This condition frequently occurs after a gastrointestinal (enteric) infection, often one caused by a specific E. coli bacteria (Escherichia coli O157:H7). It has also been associated with other enteric infections including Shigella and Salmonella and some non-enteric infections

What is Hemolytic-Uremic Syndrome?

HUS is a disorder marked by renal failure, hemolytic anemia, thrombocytopenia (platelet deficiency), coagulation defects, and variable neurological signs.

The incidence of HUS, once relatively rare, is increasing in children. It is the most common cause of acute renal failure in children. Several large outbreaks in 1992 and 1993 were attributed to undercooked hamburger contaminated with E. coli. Because of this association new labeling will appear on supermarket hamburger and temperature guidelines have been published for cooked hamburger at fast food chains and restaurants.

What are the Symptoms of Hemolytic-Uremic Syndrome?

Early symptoms:

  • Fever
  • Diarrhea
  • Blood in the stools
  • Irritability
  • Weakness
  • Lethargy

Later developing symptoms:

  • Low urine output (oliguria)
  • No urine output (anuria)
  • Pallor
  • Bruising
  • Skin rash that looks like fine red spots (petechiae)
  • Yellowish coloration to the skin (jaundice)
  • Consciousness - decreased
  • Seizures -- rare

How is Hemolytic-Uremic Syndrome Diagnosed?

Physical examination may show an enlarged liver or spleen. There may be variable, abnormal neurological changes. There is laboratory evidence of hemolytic anemia and acute renal failure.

A CBC demonstrates:

  • Decreased platelets (thrombocytopenia)
  • Rupture of red blood cells (hemolysis)
  • Anemia from loss of red blood cells (hemolytic anemia)
  • Elevated white blood count
  • The platelet count may be decreased
  • Coagulation studies such as PT and PTT may be normal or abnormal

Blood chemistry such as a chem-20 shows abnormalities:

  • The BUN is elevated
  • The creatinine is elevated
  • Free hemoglobin is elevated

A urinalysis demonstrates:

  • Blood in the urine (hematuria)
  • Protein in the urine (proteinuria)
  • A urine protein test can be used to show the amount of protein in the urine

Other tests:

  • Stool culture may be positive for a specific type of E. coli
  • Kidney biopsy (renal biopsy) shows diagnostic changes

How is Hemolytic-Uremic Syndrome Treated?

This is a serious complicating illness in both children and adults, and death may occur. The treatment is supportive.

Transfusions of packed red cells and platelets are given as needed. Kidney dialysis may be indicated. Medications prescribed include corticosteroids and aspirin.

Plasmapheresis, also called plasma exchange (or passage of the plasma through a Protein A filter) may be performed, although its role is much less well documented than in TTP (thrombotic thrombocytopenic purpura). The blood plasma (the portion that does not contain cells, but does contain antibodies) is removed and replaced with fresh (donated) plasma or filtered to remove antibodies from the circulation.

About 60% of individuals receiving treatment will recover, and the outcome is better in children.

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