Allergy is a strong reaction of the body to a substance. It is characterized by the appearance of a number of diverse symptoms: itching, sneezing, runny nose, rashes and swelling. In some situations, death is not ruled out. You can get rid of allergies only after getting rid of the allergen, but before that it needs to be detected. Allergen detection is carried out when taking a blood test for allergens.
Indications for Allergen Testing
A blood test for allergens in children and adults is indicated in the following cases:
- infancy;
- genetic predisposition;
- symptoms of an allergic reaction that develop seasonally, after direct contact with a number of substances or the consumption of certain foods;
- if the patient complains of persistent conjunctivitis, cough and runny nose;
- if it is necessary to determine the degree of violationimmune system after developing signs of an allergic reaction;
- in those situations where the therapy of dermatitis, bronchitis or conjunctivitis does not give the desired result.
Diagnosis of an allergen using skin tests
To detect an allergic reaction, it is enough to perform a general blood test, but in this case it is impossible to directly determine the allergen. That is why such a diagnostic method as skin tests is widely used.
The advantage of the technique lies in the ease of implementation and research, so that the patient receives results on the same day. The peculiarity of the procedure is the subcutaneous injection of the allergen. This diagnostic method is absolutely safe, since the amount of allergen injected is so small that it cannot have a negative effect on the body.
Allergen test results can be seen after half an hour. Even with a minor allergic reaction, redness of the skin, swelling, and a rash may occur.
There are 4 types of tests for allergens:
- subcutaneous;
- applique;
- peak test;
- scarification analysis.
The sample option is selected by the attending physician, taking into account the age group, symptoms and individual characteristics of the body.
Identification of the allergen using a blood test
A blood test for allergens is performed when necessary to diagnose various types of allergic reactions. TargetThe analysis consists in detecting antibodies to allergens in the biomaterial and setting the level of immunoglobulin E. During the determination of the results, all final figures and their values are taken into account.
A hemotest is performed to detect allergies to foods such as lactose or gluten.
Peculiarities of preparation for testing
The main part of allergological testing involves drawing blood from a vein, and this procedure requires some preparation. Thanks to high-quality preparation, you can be sure of the informativeness and reliability of the final results.
Donating blood from a vein requires compliance with the following rules:
- A blood test for allergens is performed during the period of remission of the pathology, since during an exacerbation of an allergic reaction, the number of antibodies increases significantly, which gives inaccurate results.
- It is forbidden to donate blood for viral and infectious diseases, which are characterized by an increase in body temperature.
- For 3-4 days before donating blood, it is recommended to stop using any medications.
- 5 days before blood sampling, reduce the frequency of contact with pets and exclude from the diet foods that are provocateurs of an allergic reaction.
- Before taking a blood test for allergens, it is strictly forbidden to exercise, smoke, drink coffee drinks.
- Blood is taken in the morning on an empty stomach. When testing blood for allergens in infantsblood sampling should be carried out at least 3 hours after the last meal.
Complete blood test
If there is a suspicion of an allergic reaction, the doctor gives a referral for a general blood test. Its delivery is carried out in the morning on an empty stomach, that is, the last meal should be taken no later than 12 hours before blood donation.
With this research method, the number of eosinophils is studied. If a person is he althy, then the number of these cells does not exceed 5%. If their number is exceeded, then there is a possibility of an allergic reaction. To confirm this condition, the doctor refers the patient to the delivery of immunoglobulin E.
Blood test to detect total immunoglobulin E
Immunoglobulins are antibodies that have a neutralizing effect when foreign cells enter the body. But if their number is exceeded, then this indicates the presence of an allergic reaction in the body. The higher the result, the more often the person comes into contact with the allergen.
Under normal condition and taking into account age, the body contains the following amount of immunoglobulin E (measured in mIU/ml):
- less than 2 years - up to 64;
- from 2 to 14 years - up to 150;
- over 14 years - up to 123;
- 15-60 years - up to 113;
- over 60 years - up to 114.
Detection of specific immunoglobulins
If using the previoustests could detect the presence of an allergic reaction and suggest what exactly is the allergen, then a blood test for specific allergens (specific immunoglobulins G and E are detected) will accurately determine the source of the allergic reaction.
With this research method, blood is divided into small portions and mixed with a variety of allergens. The number of substances studied can reach 190. Next, blood samples are studied by doctors, and the immune response is determined. The higher it is, the more dangerous the allergen is for a person.
How to determine the allergen by a blood test in the case of using the method of multiple chemiluminescence for diagnosis? Quite simply, since in this case special panels are used on which allergens are placed. The allergy panel is filled with the patient's blood. If there is an allergy to a specific substance, then the presence of specific antibodies can be noted in the blood sample.
There are three types of reaction when testing blood for allergens in adults and children:
- low - the substance does not pose any danger;
- medium - it is preferable to minimize contact with the allergen, if it is a food, it is recommended to exclude it from the diet;
- high – allergy is caused by this substance and contact with it should be completely avoided.
The results of a blood test for allergens are given in the form of a long table, where the patient himself can study which substances are dangerous for him.
Deciphering the analysisimmunoglobulins for an allergic reaction
Deciphering and examining a blood test for allergens in adults and children takes from 2 to 3 days. In this case, the number of immunoglobulins in plasma is studied. The norm is a small amount of these proteins, their number depends on the age of the patient.
Decryption is carried out by the attending physician, and if the amount of immunoglobulins is above the norm, then this is a clear sign of an allergic reaction. The allergen is directly determined during studies of its reaction with blood plasma.
Allergy Response Classes
To evaluate the results of the analysis, a number of classes are distinguished:
- nil (value below 0.35) - no allergic reaction due to low antibody count;
- first (indicator from 0.35 to 0.7) - due to the small amount of antibodies in the blood, an allergic reaction can develop, but is not accompanied by clinical manifestations;
- second (indicator from 0.7 to 3.5) - if the indicators have almost reached 3.5, then signs characteristic of an allergic reaction may develop;
- third (indicator from 3.5 to 17.5) - signs characteristic of an allergic reaction develop quite often;
- fourth (indicator from 17.5 to 50) - the blood contains a large amount of antibodies, which is a clear symptom of an allergic reaction;
- fifth (indicator from 50 to 100) - this result is manifested in the presence of a large number of antibodies in the human body, there is a 100% probability of an allergic reaction;
- sixth (score over 100) - develops when there is an extremely high level of antibodies.
Radioallergosorbent test method
In this case, the laboratory assistant takes blood from the patient's vein. A probable allergen is added to the obtained blood sample. If the patient has intolerance to the selected allergen, then it will be possible to observe the attachment of specific antibodies to it. After that, radioactive antibodies are added. The formed radioactive complex is read using special instruments.
Venue
Regarding the place where to take a blood test for allergens, it can be either a public clinic (it will take a long time to wait for the results) or a private company. On the territory of European countries and CIS countries, the Invitro organization is very popular (results will be received on the same or next day).
This laboratory carries out a large number of immunological studies both for whole groups of widespread allergens and for individual components. A special advantage of the organization is that you can apply here both with a referral and on your own initiative.
Obtaining the result of the analysis is carried out both when the patient visits the clinic personally, and when entering the personal account.
Actions after detecting an allergen in the blood
Getting rid of the allergen is the most effective way to deal withan allergic reaction, but it is not always possible to resort to it. That is why doctors prescribe immunotherapy and symptomatic treatment to patients.
A feature of immunotherapy is the introduction into the body of special drugs aimed at eliminating an allergic reaction. This method of treatment has a significant drawback, which is the long duration of treatment (for several years), in addition, regular visits to the doctor are required (every 2-3 weeks).
For symptomatic therapy, the action of which is aimed at getting rid of the negative signs inherent in allergies, antihistamine drugs are used ("Suprastin", "Cetirizine", "Diazolin", "Dimedrol"). This group of drugs has a neutralizing effect on free histamine and in a short time relieves a person of the symptoms inherent in allergic reactions. If after 2 days after the start of taking the medication, the symptoms do not disappear, then you should think about changing the drug.
A blood test for an allergen is a mandatory procedure if you want to identify a substance that provokes the development of allergic reactions. The type of analysis is selected directly by the attending physician, depending on the symptoms present, age and individual characteristics of the human body. If you want to get the result in a short time, it is recommended to contact a private clinic.
