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| .:: FACTS ::. |
Haemolytic uraemic Syndrome
(shortform HUS, Gasser-Syndrom)
Typical HUS
The typical form of HUS is a disease of small children, often below 4 years of age. The classical HUS is the most common reason for acute renal failure in children. An acute enteritis with watery followed by bloody diarrhea, vomiting and abdominal pain often precedes the typical triad. In the most common cases the gastroenteritis is caused by an infection with Shiga-like toxin-producing Escherichia coli. Due to the association with diarrhea, the typical HUS is also referred to as D+ (Diarrhea positive) HUS.
The classical symptoms of the HUS triad including low platelets, acute renal failure and hemolytic anemia follow a few days later. Clinical signs therefore are:
- paleness, fatigue
- oliguria / anuria
- edema
- arterial hypertension
- proteinuria / hematuria
Clues for D+HUS in the laboratory testing:
- fragmented erythrocytes
- hemoglobin <10 mg/dl
- elevated creatinine
- low haptoglobin
- low platelets
Beside hematological and renal complication extra-renal manifestation, like central nervous system, gastrointestinal and cardial symptoms, are
Treatment of the typical HUS is supportive (fluid, electrolyte, antihypertensive drugs) and renal replacement therapy.
Atypical HUS
The atypical hemolytic uremic syndrome is a rare subgroup of patients with HUS who share some features, like recurrence of the disease, no causal infection with EHEC prior to disease onset and a poorer outcome. The etiology as well as the pathogenesis of the disease is not fully understood yet. There is a familial and a sporadic form of atypical HUS.
Scientific work so far has shown that the Complement System, a part of our own innate immunity, plays a keyrole in the pathogenesis of this disease. Several mutations within Complement proteins or Complement regulatory proteins, like Factor H, Factor I, Factor B, Factor C3, Factor H Related Proteins, MCP and Thrombomodulin, were discovered so far. The genetic alterations result in pathological overactivation of the Complement System (especially the alternative pathway) leading to celllysis through activation of the Terminal Complement Complex (TCC). Additionally to mutations in Complement proteins a small part of patients have antibodies against Factor H, often associated with mutations in Factors H Related Protein 1 and 3.
The clinical presentation is characterized through the typical triad of hemolytic anemia, thrombocytopenia and renal failure. The atypical form of HUS differs from the classical form in points of disease recurrence, poorer outcome and progression to endstage renal disease (ESRD).
Clinical and laboratory findings are:
- fragmented erythrocytes
- hemoglobin <10 mg/dl
- elevated creatinine
- elevated LDH
- Complement consumption (low C3)
Treatment and long term prognosis is depending on underlying defect, but plasma therapy is considered as first line treatment option.
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