Hemolytic uremic syndrome (HUS) most often affects young children and causes acute kidney damage. Find out what the symptoms of hemolytic uremic syndrome are, is it preventable and how is it treated?
Hemolytic uremic syndrome(hemolytic uremic syndrome) is a multi-organ disease diagnosed most often in young children. In the course of haemolytic uremic syndrome, acute kidney damage occurs. Blood coagulation disorders, leading to changes in the blood supply to internal organs, are also a significant abnormality.
Contents:
- Hemolytic uremic syndrome - what is it?
- Hemolytic uremic syndrome - types and symptoms
- Hemolytic uremic syndrome - in whom can it occur?
- Hemolytic uremic syndrome - prophylaxis
- Hemolytic uremic syndrome - diagnosis
- Hemolytic uremic syndrome - treatment
- Hemolytic uremic syndrome - complications
There are different causes of haemolytic uremic syndrome, the most common of which is infection with certain types of bacteria. These bacteria, most often acquired through food, produce toxins that lead to the onset of disease symptoms.
Hemolytic uremic syndrome is a serious condition that can lead to chronic kidney dysfunction.
Hemolytic uremic syndrome - what is it?
The term "hemolytic uremic syndrome" sounds quite complicated and may be completely incomprehensible to laymen. To understand the essence of the disease, let's first try to decode the individual elements of its name.
The term haemolytic results from the hemolysis that occurs in this syndrome, i.e. the process of disintegration of red blood cells. The effect of haemolysis is anemia, i.e. a decrease in the number of erythrocytes in the blood.
The second part of the syndrome's name - uremia - denotes a condition in which the kidneys are unable to perform their excretory function properly. Then, harmful products of metabolism accumulate in the body. Their accumulation can lead to serious damage to organs.
We already know two components of the hemolytic uremic syndrome:
- breakdown of red blood cells
- acute renal failure
What other processes take place during the course of the disease?
Very important changes concern the coagulation system and the inside of small blood vessels. In hemolytic uremic syndrome, the endothelium, i.e. the layer that is the inner lining of the vessels, is damaged.
Disruption of the endothelial function leads to the formation of blood clots, clogging the lumen of the vessels. Closed vessels, in turn, cause disturbances in the blood supply to the organs.
Such vascular changes first appear in the kidneys, which explains the occurrence of acute renal failure.
In the coagulation system, a typical symptom of hemolytic uremic syndrome is thrombocytopenia, i.e. a reduction in the number of platelets.
Hemolytic uremic syndrome - types and symptoms
Now that we know what pathologies are part of the hemolytic uremic syndrome, it's time to ask ourselves: what is the cause of them?
Due to the etiology of the disease, there are 2 forms of hemolytic uremic syndrome: typical and atypical.
The typical form of hemolytic uremic syndromeaccounts for approximately 90% of all cases of the disease.
The causative agent of this form of hemolytic uremic syndrome is bacteria, or more precisely - their toxins. The Escherichia coli serotype (variant) O157: H7 is considered to be the most common pathogen causing haemolytic uremic syndrome. It also happens that the disease is caused by other strains of bacteria (e.g. Shigella ).
The common feature of all these pathogens is the way they are acquired - they enter the body with food.
For this reason, the first symptoms of hemolytic uremic syndrome, in a typical variant, come from the gastrointestinal tract. They are:
- stomach pains
- diarrhea with blood
- and sometimes vomiting
After some time, symptoms of damage to other organs join them:
- anemia
- acute renal failure
- thrombocytopenia (which may lead to bleeding)
Atypical hemolytic uremic syndromeis not caused by the action of bacterial toxins.
It is caused by disturbances in the functioning of the immune system, and more precisely one of its components - the so-called complement system. The effects of an abnormal immune response are the same as in the typical hemolytic uremic syndrome: the cells are damagedvascular endothelium and the formation of blood clots in tiny vessels, which can lead to kidney damage.
In atypical hemolytic uremic syndrome there are no initial symptoms of the gastrointestinal tract - e.g. no characteristic diarrhea.
This form of hemolytic uremic syndrome is sometimes preceded by an infection of the upper respiratory tract.
Another cause of atypical hemolytic uremic syndrome is an inherited variation in the functioning of the immune system (genetic predisposition). In this case, the symptoms of the disease may run in families and they have a tendency to recur.
Atypical hemolytic uremic syndrome is more severe and associated with a more severe prognosis than the typical variant.
Hemolytic uremic syndrome - in whom can it occur?
Hemolytic uremic syndrome is a childhood disease. The greatest incidence occurs in the youngest children and occurs under the age of 5.
Hemolytic uremic syndrome is also the most common cause of acute renal failure in this age group.
This does not mean, however, that patients of other age cannot develop this disease.
Haemolytic uremic syndrome also happens in adults and is usually much more severe in adults.
Hemolytic uremic syndrome - prophylaxis
Is it possible to prevent the development of hemolytic uremic syndrome?
In the case of the typical E. Coli (or other) toxin-induced variant, prevention is avoiding eating potentially contaminated foods. The most common source of such bacteria is inadequately prepared meat - raw and / or undercooked. It is also important to drink water from properly controlled sources.
There are discussions in the scientific world about the appropriateness of using antibiotics in the presence of bloody diarrhea caused by E.Coli .
It might seem that the use of an antibiotic would avoid hemolytic uremic syndrome caused by bacterial toxins.
However, there are scientific studies confirming the fact that the use of an antibiotic causes the sudden destruction of large numbers of bacterial cells, which when broken down release a huge amount of toxin into the bloodstream.
For this reason, antibiotics are not routinely used to prevent hemolytic uremic syndrome.
Hemolytic uremic syndrome - diagnosis
The first step in the diagnosis of hemolytic uremic syndrome is a medical history and a physical examination aimed at the characteristic symptoms of thisailments.
The typical course of the disease is initial diarrhea with blood, followed by fever and severe weakness, and over time the volume of urine output is reduced.
The spectrum of hemolytic uremic syndrome symptoms is wide, however, and the above symptoms may not be present in all patients.
Complications of hemolytic uremic syndrome, such as arterial hypertension, jaundice or seizures, are sometimes revealed on physical examination.
A blood test is required to detect the typical features of hemolytic uremic syndrome. As a result of haemolysis (breakdown of red blood cells), a decrease in the number of red blood cells may be observed in the blood smear.
Fragments of damaged blood cells are visible under the microscope - these are the so-called schistocytes. Another characteristic change is thrombocytopenia (a decrease in the number of platelets in the blood).
Kidney dysfunction can be detected by marking the so-called renal parameters. They include, among others urea and creatinine levels. Increasing the value of these indicators indicates the development of renal failure. As a result of kidney dysfunction, electrolyte disturbances may also develop.
In the diagnosis of hemolytic uremic syndrome, one more test is important: stool culture for bacteria that may be the cause of the disease. Typically E. coli O157: H7 or Shigella strains are searched for. Additionally, it is possible to determine the presence of a bacterial toxin in the stool.
The diagnosis of atypical hemolytic uremic syndrome is slightly different and more complex. It requires detailed immunological and sometimes genetic tests to identify the source of disorders in the immune system.
Hemolytic uremic syndrome - treatment
So far, there is no causal treatment for hemolytic uremic syndrome. Therapy involves the use of a variety of symptomatic treatments. In case of severe anemia, it may be necessary to transfuse blood products (red blood cell concentrate).
Similarly, severe thrombocytopenia may require a platelet concentrate transfusion.
Renal failure may be an indication for the implementation of renal replacement therapy (peritoneal dialysis, hemodialysis or hemodiafiltration).
If a patient develops arterial hypertension, medications that lower blood pressure are also used.
The main method of treatment of atypical hemolytic uremic syndrome is plasmapheresis, i.e. the purification of blood plasma. This procedure cleans the blood of molecules produced by the immune system,which lead to the onset of symptoms of the disease.
There is also a drug reserved for this variant of hemolytic uremic syndrome called Ekulizumab. It is a preparation that inhibits the excessive activity of the complement system, which is the main "culprit" responsible for the development of atypical ZHM.
Hemolytic uremic syndrome - complications
Hemolytic uremic syndrome is a serious condition that can lead to chronic complications and even death. Mortality in the hemolytic uremic syndrome is estimated at 5%.
The main complication of hemolytic uremic syndrome is chronic kidney disease - it affects, depending on the source, from 30 to 50% of patients.
Patients after the disease should be under the constant supervision of the nephrology clinic. End-stage renal disease may be the reason for eligibility for a kidney transplant procedure. Kidney damage can also cause arterial hypertension (the kidney has a significant impact on the regulation of blood pressure through the production of a hormone called renin).
The most serious prognosis in hemolytic uremic syndrome concerns adult patients, patients with the atypical form of this syndrome, and those with involvement of organs other than the kidneys (e.g. the central nervous system).
About the author
Krzysztof BialaziteA medical student at Collegium Medicum in Krakow, slowly entering the world of constant challenges of the doctor's work. She is particularly interested in gynecology and obstetrics, paediatrics and lifestyle medicine. A lover of foreign languages, travel and mountain hiking.
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