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.

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

• 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

• A complete blood count (CBC) might show:
  • Decreased platelet count (thrombocytopenia)
  • Rupture of red blood cells
  • Anemia from loss of red blood cells (hemolytic anemia)
  • Elevated white blood count
• Coagulation studies such as PT and PTT may be normal or abnormal.
• Blood chemistry such as a chem-20 shows abnormalities, such as:
  • BUN is elevated
  • Creatinine is elevated
  • Free hemoglobin is elevated
• A urinalysis demonstrates:
  • Blood in the urine
  • Protein in the urine
• A urine protein test can be used to show the amount of protein in the urine.

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

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 filter) may be performed, although its role is not completely clear.

In plasmapharesis, 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.

• Chronic or relapsing HUS
• Acute renal failure
• Chronic renal failure
• Uremia (symptoms caused by accumulation of nitrogen-containing wastes in the body)