Hemolytic-uremic syndrome (HUS)

Alternative names

HUS

Definition

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

Causes, incidence, and risk factors

This disorder is most common in children. It 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.

HUS, once relatively rare, is increasing in children. It is the most common cause of acute kidney failure in children. Several large outbreaks in 1992 and 1993 were attributed to undercooked hamburger contaminated with E. coli. Because of this association, supermarket hamburger has new labeling, and there are new temperature guidelines for hamburger cooked at fast-food chains and restaurants.

HUS is less common in adults. Most adult cases have been reported in patients with cancer who have received the chemotherapy drug 5-FU.

Predisposing risk factors are not known. HUS occasionally occurs in association with a variety of other diseases and infections. About 1 in 10,000 people get it.

HUS often begins with vomiting and diarrhea (which may be bloody). Within a week, the patient develops weakness and irritability. Urine output decreases dramatically and may almost cease. Because red blood cells are being destroyed (a process called hemolysis), the patient rapidly becomes anemic and pale.

Symptoms

Early symptoms:

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

Later developing symptoms:

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

Signs and tests
A physical examination may show an enlarged liver or spleen. There may be variable, abnormal nervous system changes. There is laboratory evidence of hemolytic anemia and acute renal failure.