Hemolytic-uremic syndrome

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at August 4, 2016
StartDiseasesHemolytic-uremic syndrome

Hemolytic-uremic syndrome, or HUS for short, is a disease that affects the kidneys. HUS is a disease that predominantly affects children. In children, it is most commonly caused by an infection of the gastrointestinal tract with a strain of Escherichia coli (E. coli). While not well known outside medical circles, hemolytic-uremic syndrome is estimated to affect 6.1 children out of every 100,000 children aged 5 years or younger.

Contents

Definition & Facts

Cases of hemolytic-uremic syndrome have been documented since as early as 1955. It is a kidney disease that can cause temporary or permanent injury or even acute kidney failure. Hemolytic-uremic syndrome involves the destruction of red blood cells. The dead red blood cells begin to build up in the glomeruli which are the network of blood vessels in the kidneys that help filter out waste. This accumulation of dead red blood cells blocks the kidneys' ability to filter toxins out of the bloodstream. Blocked kidneys can quickly become injured or nonviable kidneys. 

The most common culprit causing the destruction of the red blood cells is a strain of E. coli bacteria that produces the Shiga toxin. Approximately 10 percent of cases are not caused by E. coli, and they are labeled atypical hemolytic-uremic syndrome. Atypical hemolytic-uremic syndrome may be caused by HIV/AIDS, infection with Streptococcus bacteria, chemotherapy, pregnancy, and a variety of other infections and health conditions.

The number of worldwide reported cases of Hemolytic-uremic syndrome is thought to be growing. Hemolytic-uremic syndrome is more likely to affect the following individuals:

  • Children ages 5 years and under.
  • Older individuals with weakened immune systems.
  • Individuals living in rural areas.
  • Individuals that live or work in close contact with farm animals.
  • Individuals that have certain heritable genetic mutations

More cases of HUS are typically reported when the weather is warm than in fall or winter.

Symptoms & Complaints

Most children that develop hemolytic-uremic syndrome will first experience an E. coli infection that includes between two and 14 days of diarrhea symptoms. Other commonly reported symptoms of HUS onset include the following:

As hemolytic-uremic syndrome progresses, it can cause anemia. Anemia occurs when there are not enough red blood cells to carry oxygen to all the cells in the body. Because the onset of hemolytic-uremic syndrome is often confused with gastroenteritis (inflammation of the stomach and intestinal lining), it is critical to obtain an accurate diagnosis before beginning a course of treatment. 

Causes

In an estimated 90 percent of reported cases, the predominant causes for HUS are linked to a form of E. coli (Escherichia coli) bacteria. While E. coli live in the intestines and contribute to digestion, a particular strain of E. coli, Escherichia coli O157:H7 causes severe illness and infection. It is transmitted through undercooked meat, contaminated raw vegetables or fruits, or swimming in a pool or lake that has the bacteria.

Atypical hemolytic-uremic syndrome is a classification that describes any cases of hemolytic-uremic syndrome that aren't caused by E. coli. It often has comorbidity and possible causal correlation with organ transplantation (including bone marrow transplantation), antiphospholipid antibody syndrome, scleroderma, and cancer among other conditions.

Diagnosis & Tests

Diagnosing HUS begins with the physician taking a complete individual medical history and family history followed by a thorough physical examination. From here, tests are usually ordered:

Treatment & Therapy

Once an individual has received a positive diagnosis of hemolytic-uremic syndrome, the treatment phase can begin. With prompt and appropriate treatment, the outcome for most patients is positive. Typically, treatment focuses on supporting the individual's recovery from the infection and preventing kidney damage. Often the individual undergoing treatment will need to be hospitalized.

Treatment will also involve continuously and closely monitoring the individual for more serious complications, which can include seizures, failure to clot, high blood pressure, kidney injury or disease, coma or even stroke. Assuming there is no kidney damage, the patient will probably be able to recover without incident. Depending on the side effects and/or complications that may arise, HUS treatment may include any or all of the following:

Prevention & Prophylaxis

The majority of cases of hemolytic-uremic syndrome may be avoided to the extent that one can avoid infection with E. coli through proper food handling. However, full prevention can be difficult because it can be challenging to detect when and where E. coli contamination has occurred in lieu of government-announced investigations and recalls of unsafe food products. Some methods that may help prevent a person from developing hemolytic-uremic syndrome include:

  • Avoiding swimming in potentially contaminated swimming holes, ponds, rivers or pools.
  • Avoiding drinking anything that has not been pasteurized.
  • Avoiding eating undercooked or raw meat and not letting raw frozen meat thaw on the countertops.
  • Keeping food preparation and eating areas and utensils very clean and sanitary.
  • Cooking meat at least to 160 °F (71 °C) and reheat meat to 165 °F (74 °C)
  • Always washing hands after using the restroom, changing diapers and after preparing raw meats.
  • Always keeping and storing raw produce and meat items separate from each other.
  • Preventing children who have had diarrhea from swimming in public places.
  • Always practicing good personal hygiene.