Causes and association with intestinal infections
The primary trigger for the development of HUS in children is infection with enterohemorrhagic Escherichia coli (EHEC), among which the O157:H7 serogroup dominates (as well as O157:HNM and O104:H4). Sheep and cattle serve as the reservoir for these bacteria.
Transmission occurs via the alimentary route — typically through insufficiently cooked meat. In children of all ages (except the first months of life), such an infection can manifest as hemorrhagic colitis with bloody diarrhea and carry a high risk of severe systemic complications, primarily hemolytic-uremic syndrome.
Pathogenesis and classification
From the point of view of the general classification of hemolytic conditions, HUS belongs to acquired microangiopathic anemias (this category also includes atypical aHUS and thrombotic thrombocytopenic purpura).
Mechanism of development: It is based on vascular bed damage with the formation of microthrombi. Passing through such vessels, erythrocytes are mechanically traumatized and fragmented, leading to massive intravascular hemolysis.
Simultaneously, microthrombi occlude intrarenal vessels, which directly leads to the development of acute renal failure (ARF).
Clinical presentation and the "sinister triad"
The full-blown clinical picture of HUS consists of laboratory abnormalities and organ damage. The classic "sinister triad" of symptoms is distinguished:
- Anemia — a sharp drop in hemoglobin levels due to erythrocyte destruction.
- Thrombocytopenia — a significant decrease in the platelet count in the blood.
- Anuria (or oligoanuria) — a sharp reduction in urine output (less than 400 ml per day), reflecting severe renal damage.
Additionally, laboratory tests record a critical increase in nitrogenous waste products — urea and creatinine.
Patient management tactics
The development of HUS in escherichiosis infection requires immediate resuscitation measures. The main tactical objective in the event of acute renal failure and severe impairment of renal filtration function is emergency transfer of the patient to hemodialysis.
HUS stands for Hemolysis, Uremia (nitrogenous waste), Suppressed platelets and urine (triad: anemia, thrombocytopenia, anuria).
Class and exam questions
Which bacterium most frequently causes HUS?
Enterohemorrhagic Escherichia coli serogroup O157:H7 (EHEC), the source of which is cattle and sheep.
What does the "sinister triad" of hemolytic-uremic syndrome include?
Anemia, anuria, and thrombocytopenia against the background of rising nitrogenous waste in the blood.
What is the emergency management strategy for HUS development?
The patient is indicated for emergency transfer to hemodialysis due to the development of acute renal failure.
What else to study on this topic
- Clinical variants of other escherichioses (ETEC and EIEC)
- Differential diagnosis of hereditary and acquired hemolytic anemias
- Stages of acute renal failure and the shock phase
- Morphological changes in acute tubular necrosis
- Pathogenesis of thrombotic thrombocytopenic purpura (TTP)
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