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Hemolytic-uremic syndrome
Last reviewed: 23.04.2024
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Hemolytic-uremic syndrome is a diverse on the etiology, but similar in clinical manifestations of the symptom complex, manifested by hemolytic anemia, thrombocytopenia and arthritis.
Hemolytic-uremic syndrome was first described as an independent disease by Gasser et al. In 1955, characterized by a combination of microangiopathic hemolytic anemia, thrombocytopenia and acute renal failure, in 45-60% of cases ends lethal.
About 70% of hemolytic-uremic syndrome is described in children of the first year of life, beginning with the month of age, the rest - in children older than 4-5 years and single cases in adults.
The severity of hemolytic-uremic syndrome determines the degree of anemia and the degree of renal function impairment; the prognosis is more serious the longer the anuria period is.
Causes of hemolytic-uremic syndrome
Hemolytic-uremic syndrome is the main cause of acute renal failure in children aged 6 months to 3 years and possible - in older children. The development of HUS is associated with OCI caused by enterohemorrhagic E. Coli 0157: H7, which is capable of producing Shiga toxin. After 3-5 days from the onset of the disease, there is a progressive decrease in diuresis up to full anuria. The episode of hemolysis and hemoglobinuria in children is usually not diagnosed.
From modern positions, in the pathogenesis of hemolytic-uremic syndrome, microbial or viral toxic damage to the endothelium of the capillaries of the renal glomeruli, the development of DIC syndrome and mechanical damage to erythrocytes are of primary importance. It is believed that red blood cells are damaged mainly by passage through the capillaries of the kidney glomeruli, filled with clots of fibrin. In turn, the destroyed red blood cells have a damaging effect on the vascular endothelium, supporting the DIC syndrome. In the process of blood coagulation there is active absorption from the circulation of platelets and clotting factors.
Thrombosis of the renal glomeruli and of the bringing arteries is accompanied by severe hypoxia of the renal parenchyma, necrosis of the epithelium of the renal tubules, edema of interstitial kidneys. This leads to a drop in the rate of plasma flow and filtration in the kidneys, a sharp decrease in their concentration ability.
The main toxins contributing to the development of hemolytic-uremic syndrome are Shiga toxin causative agents of dysentery and shiga-like toxin type 2 (verotoxin), usually secreted by E. Coli 0157 serum (other enterobacteria can also secrete it). In young children in capillaries of the renal glomeruli, the receptors to these toxins are represented to the greatest extent, which contributes to the damage of these vessels, followed by local ihotrombification due to the activation of blood coagulation. In older children, circulating immune complexes (CIC) and complement activation, which contribute to damage to renal vessels, have a leading role in the pathogenesis of HUS.
Symptoms of hemolytic-uremic syndrome
There is also a special form of HUS, which is characterized by a congenital, genetically conditioned lack of production of prostacyclin by endotheliocytes of the vascular wall. This substance prevents aggregation (gluing) of platelets near the vascular wall and thereby prevents the activation of the vascular-platelet unit of hemostasis and the development of hypercoagulation.
Suspicion of hemolytic-uremic syndrome in a child with clinical symptoms of acute intestinal infections or acute respiratory viral infection occurs more often with a rapid decrease in diuresis against the background of normal HEO parameters and in the absence of signs of dehydration. The appearance of vomiting, fever during this period already indicates the presence of hyperhydration, edema of the brain. The clinical picture of the disease is supplemented by the growing pallor of the skin (skin with a yellowish tinge), sometimes hemorrhagic rashes on the skin.
Diagnosis of hemolytic-uremic syndrome
In the diagnosis of hemolytic uremic syndrome, the detection of anemia (usually a level of Hb <80 g / l), fragmented erythrocytes, thrombocytopenia (105 ± 5.4-10 9 / L), moderate increase in the concentration of indirect bilirubin (20-30 μmol / L) urea (> 20 mmol / l), creatinine (> 0.2 mmol / l).
Diagnosis of hemolytic-uremic syndrome
What tests are needed?
Treatment of hemolytic-uremic syndrome
In the recent past, the majority of HUS patients died - the mortality rate reached 80-100%. The creation of a method for purifying blood with the help of "artificial kidney" apparatus changed the situation. In the best clinics of the world, the mortality rate now ranges from 2-10%. Lethal outcome is often due to late diagnosis of this syndrome and the development of irreversible brain changes due to its edema, less often (in the late period) it is associated with nosocomial pneumonia and other infectious complications.
Children with hemolytic uremic syndrome require 2 to 9 hemodialysis sessions per course (daily) for treatment of acute renal failure. With the help of dialysis, close to the normal values of metabolites, VEO, hyperhydration, edema of the brain and lungs are prevented.
In addition, the complex treatment of children with hemolytic-uremic syndrome includes the introduction of blood components when they are deficient (erythrocyte mass or washed erythrocytes, albumin, SZP), anticoagulant therapy with heparin, the use of broad-spectrum antibiotics (usually cephalosporins of the third generation), drugs , improving microcirculation (trental, euphyllin, etc.), symptomatic agents. In general, experience shows that the earlier a child enters a specialized hospital (before the development of a critical condition), the greater the probability of a successful, complete and rapid cure.
In the pre-dialysis period, a fluid restriction is necessary; it is prescribed from the calculation: diuresis for the previous day + volume of pathological losses (stool and vomiting) + volume of perspiratory losses (in norm from 15 to 25ml / kg per day) (depending on age). This total volume of fluid is injected fractional, preferably inside. Before the start of dialysis therapy, it is desirable to limit the intake of table salt, during dialysis and recovery of diuresis, we practically do not restrict children in salt intake.
Forecast for hemolytic-uremic syndrome
When the duration of the oligoanuscular period is more than 4 weeks, the prognosis for recovery is uncertain. Prognostically unfavorable clinical and laboratory signs are persistent neurological symptoms and the absence of a positive reaction to the first 2-3 sessions of hemodialysis. In previous years almost all children of early age with hemolytic-uremic syndrome died, but with the use of hemodialysis, the mortality rate decreased to 20%.