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Hemolytic uremic syndrome.
Last reviewed: 12.07.2025
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Hemolytic uremic syndrome is a symptom complex of diverse etiology but similar clinical manifestations, manifested by hemolytic anemia, thrombocytopenia and acute renal failure.
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, and is fatal in 45-60% of cases.
About 70% of hemolytic uremic syndrome is described in children of the first year of life, starting from the age of one month, the rest - in children over 4-5 years old and isolated cases in adults.
The severity of hemolytic uremic syndrome is determined by the degree of anemia and the degree of renal dysfunction; the longer the period of anuria, the more serious the prognosis.
[ 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 acute intestinal infection caused by enterohemorrhagic intestinal bacteria 0157:H7, capable of producing Shiga toxin. After 3-5 days from the onset of the disease, a progressive decrease in diuresis is observed up to complete anuria. An episode of hemolysis and hemoglobinuria in children is usually not diagnosed.
From a modern standpoint, the pathogenesis of hemolytic uremic syndrome is primarily affected by microbial or viral toxic damage to the endothelium of the renal glomerular capillaries, the development of DIC syndrome, and mechanical damage to erythrocytes. It is believed that erythrocytes are damaged mainly when passing through the capillaries of the renal glomeruli filled with fibrin clots. In turn, destroyed erythrocytes have a damaging effect on the vascular endothelium, maintaining DIC syndrome. During the process of blood coagulation, platelets and coagulation factors are actively absorbed from the circulation.
Thrombosis of the renal glomeruli and afferent arteries is accompanied by severe hypoxia of the renal parenchyma, necrosis of the epithelium of the renal tubules, and edema of the renal interstitium. This leads to a decrease in the rate of plasma flow and filtration in the kidneys, and a sharp decrease in their concentration capacity.
The main toxins that contribute to the development of hemolytic uremic syndrome are considered to be Shiga toxin of dysentery pathogens and Shiga-like toxin type 2 (verotoxin), usually secreted by Escherichia coli serovar 0157 (it can also be secreted by other enterobacteria). In young children, receptors to these toxins are most abundant in the capillaries of the renal glomeruli, which contributes to damage to these vessels with subsequent local thrombosis due to activation of blood clotting. In older children, circulating immune complexes (CIC) and complement activation, which contribute to damage to the renal vessels, are of leading importance in the pathogenesis of HUS.
Symptoms of hemolytic uremic syndrome
A special form of HUS is also distinguished, which is characterized by a congenital, genetically determined deficiency in the production of prostacyclin by endothelial cells of the vascular wall. This substance prevents the aggregation (sticking together) of thrombocytes near the vascular wall and thereby prevents the activation of the vascular-thrombocyte link 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 infections often occurs with a rapid decrease in diuresis against the background of normal parameters of the urinary excretion system and in the absence of signs of dehydration. The appearance of vomiting and fever during this period already indicates the presence of hyperhydration and cerebral edema. The clinical picture of the disease is complemented by increasing pallor of the skin (skin with a yellowish tint), sometimes hemorrhagic rashes on the skin.
Diagnosis of hemolytic uremic syndrome
In the diagnosis of hemolytic uremic syndrome, detection of anemia (usually Hb level < 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) helps.
What tests are needed?
Treatment of hemolytic uremic syndrome
In the recent past, most patients with HUS died - the mortality rate reached 80-100%. The creation of a method for purifying blood using "artificial kidney" devices changed the situation. In the best clinics in the world, the mortality rate currently fluctuates between 2-10%. A fatal outcome is often due to late diagnosis of this syndrome and the development of irreversible changes in the brain due to its edema, less often (in the late period) it is associated with hospital-acquired pneumonia and other infectious complications.
Children with hemolytic uremic syndrome require 2 to 9 hemodialysis sessions per course (daily) of ARF treatment. Dialysis maintains near-normal metabolite and VEO indices, prevents hyperhydration, cerebral and pulmonary edema.
In addition, the treatment complex for children with hemolytic uremic syndrome includes the introduction of blood components in case of their deficiency (erythrocyte mass or washed erythrocytes, albumin, FFP), anticoagulant therapy with heparin, the use of broad-spectrum antibiotics (usually 3rd generation cephalosporins), drugs that improve microcirculation (trental, euphyllin, etc.), symptomatic agents. In general, experience shows that the earlier a child is admitted to a specialized hospital (before the development of a critical condition), the greater the likelihood of successful, complete and rapid recovery.
In the pre-dialysis period, fluid restriction is necessary; it is prescribed based on the following calculation: diuresis for the previous day + volume of pathological losses (stool and vomiting) + volume of perspiratory losses (normally from 15 to 25 ml/kg per day) (depending on age). This total volume of fluid is administered fractionally, mainly orally. Before the start of dialysis therapy, it is advisable to limit the consumption of table salt; during periods of dialysis and restoration of diuresis, we practically do not limit children in salt intake.
Prognosis for hemolytic uremic syndrome
If the oligoanuric period lasts more than 4 weeks, the prognosis for recovery is questionable. Prognostically unfavorable clinical and laboratory signs are persistent neurological symptoms and the absence of a positive response to the first 2-3 hemodialysis sessions. In previous years, almost all young children with hemolytic uremic syndrome died, but with the use of hemodialysis, the mortality rate has decreased to 20%.
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