Hemolytic-uremic syndrome (HUS for short) is the most common cause of kidney failure in children. The disease primarily affects the blood vessels, blood cells, and the kidneys: Starting with a bacterial infection of the gastrointestinal tract, damage occurs to the walls of the blood vessels, which can affect a number of organs. The bacteria release toxins that attack not only the blood vessel walls but also the renal tubules. Hemolytic-uremic syndrome primarily affects infants and toddlers, but adults with compromised immune systems can also be affected.
Below you will find further information on hemolytic-uremic syndrome as well as a list of selected HUS specialists.
Symptoms of Hemolytic-Uremic Syndrome
On average, one to three days after infection with a bacterial pathogen (including EHEC), the following symptoms appear:
- watery, and later bloody, diarrhea
- vomiting
- fever
- abdominal cramps and colic
In addition to affecting the gastrointestinal tract, the bacteria’s toxins also impair blood flow to the brain. This can lead to lethargy, hyperexcitability, seizures, or other neurological symptoms.
There are also so-called atypical forms of hemolytic-uremic syndrome. These are rare and are usually genetically caused. Atypical hemolytic-uremic syndrome occurs in episodes, which are often triggered by a respiratory or gastrointestinal infection. The symptoms generally mirror those of the bacterial form.
Diagnosis: Pathogen Detection and Blood Analysis
If hemolytic uremic syndrome is suspected based on characteristic symptoms, the diagnosis is confirmed through blood and urine tests. In the event of the disease, the following parameters can be determined through laboratory analysis:
- Decrease in hemoglobin levels with anemia
- Decrease in the lifespan of red blood cells (erythrocytes) to less than 100 days (hemolysis)
- Damaged red blood cells (fragmented red blood cells)
- Decrease in platelet concentration (thrombocytopenia)
- Increased urea and creatinine levels (uremia)
Blood components under the microscope: erythrocyte (red blood cell), thrombocyte (platelet), leukocyte (white blood cell)
In addition, a bacterial pathogen is detected in the blood. If none can be found, genetic testing may be considered to confirm the diagnosis of atypical hemolytic-uremic syndrome.
Treatment of hemolytic-uremic syndrome
To date, there is no causal treatment for hemolytic-uremic syndrome. Therefore, supportive care and, if necessary, intensive care are typically provided.
Treatment of Bacterial Hemolytic Uremic Syndrome
Since the underlying bacterial infection resolves within 5 to 10 days, antibiotic treatment should not be administered during the acute phase (diarrhea phase). Antibiotics are suspected of causing bacterolysis (breakdown of bacteria). This accelerates the release of the disease-causing toxin and thus leads to a worsening of the patient’s condition.
Instead, plasmapheresis can be used to reduce the concentration of toxins in the bloodstream. In this procedure, blood plasma is removed from the body and replaced with frozen fresh plasma. Treatment with corticosteroids or H1 and H2 blockers is often administered beforehand to prevent an allergic reaction.
In severe cases and when plasmapheresis is unsuccessful, drug therapy with the antibody eculizumab may be indicated. In some cases, plasmapheresis and eculizumab are also administered as combination therapy.
An analysis of HUS cases during the 2011 EHEC epidemic in Germany showed that a “best supportive care” approach—in which the best possible supportive treatment measures are taken—yields results similar to those of plasma exchange, at least in the short term. For example, high blood pressure (hypertension) is treated with antihypertensive medications.
If severe anemia results from a shortened red blood cell survival time (hemolytic anemia), red blood cell transfusions are required. If life-threatening bleeding occurs due to a low platelet count, platelet concentrates are administered. If renal insufficiency is present with fluid retention (edema, ascites, anasarca) as well as heart failure with pulmonary edema, dialysis is necessary.
Treatment of Atypical Hemolytic-Uremic Syndrome
Atypical hemolytic-uremic syndrome is caused, among other things, by gene mutations that negatively interfere with the innate (nonspecific) immune response. The exact underlying mechanisms are not yet fully understood, which is why many of the therapeutic approaches are still being tested in clinical trials.
The treatment of choice is a combination therapy consisting of plasmapheresis and/or plasma infusions, as well as administration of fresh frozen plasma. In certain forms of atypical hemolytic-uremic syndrome, eculizumab—which inhibits the dysregulation of the nonspecific immune response—can lead to an improvement in symptoms.
If the disease is due to a deficiency of a specific protein involved in the innate immune response (known as complement factor H), a liver transplant may be considered. If end-stage renal failure is also present, a simultaneous kidney transplant is considered.
Immunosuppression (suppression of the immune system) may also be indicated for some forms of atypical hemolytic-uremic syndrome.
If the cause of the disease is a substance contained in other medications, these medications must be discontinued.
Prognosis and Course of Recovery for Hemolytic-Uremic Syndrome
For infants who respond well to treatment, the prognosis is generally good. Since dialysis is now initiated early on, the survival rate is over 95 percent.
In some cases, despite successful treatment and normalization of parameters, renal failure may develop even years later. For example, up to 70 percent of patients with atypical hemolytic uremic syndrome develop end-stage renal failure, which leads to the need for dialysis and, in the long term, requires a kidney transplant.
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