Allergy is a strong reaction of an organism 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 excluded. You can get rid of allergies only after getting rid of the allergen, but before that you need to detect it. Identification of the allergen is carried out upon delivery of a blood test for allergens.
Indications for the analysis of allergens
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 use of certain foods;
- if the patient has complaints of persistent conjunctivitis, cough and runny nose;
- if necessary, determine the degree of violation of the immune system, after the development of signs of an allergic reaction;
- in those situations where the treatment of dermatitis, bronchitis or conjunctivitis does not give the desired result.
Diagnosis of allergen with 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 advantages of the technique are the simplicity of conducting and research, so that the patient receives the results on the same day. A feature of the procedure is the subcutaneous administration of an allergen. This diagnostic method is absolutely safe, since the amount of allergen administered 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, rash may occur.
There are 4 types of samples for allergens:
- subcutaneous
- application;
- peak test;
- scarification analysis.
The sample variant is selected by the attending physician taking into account the age group, symptoms and individual characteristics of the body.
Blood Allergen Detection
A blood test for allergens is performed if necessary to diagnose various types of allergic reactions. The purpose of the analysis is to detect antibodies to allergens in the biomaterial and to establish the level of immunoglobulin E. During the determination of the results, all final numbers and their values are taken into account.
To detect allergies to products, for example, lactose or gluten, a blood test is performed.
Features of preparation for passing tests
The main part of allergological studies includes the removal of blood from a vein, and for this procedure, some preparation is required. Thanks to quality training, you can be sure of the information content and the reliability of the final results.
Blood donation 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 the 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.
- 3-4 days before blood donation, it is recommended to abandon the use of any medication.
- 5 days before the blood is taken, the frequency of contacts with pets should be reduced and foods that provoke an allergic reaction should be excluded from the diet.
- 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 analyzing blood for allergens in infants, blood sampling should be carried out no less than 3 hours after the last meal.
Complete blood count
If there is a suspicion about the presence of an allergic reaction, then 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 carried out no later than 12 hours before blood donation.
With this research method, the number of eosinophils is studied. If a person is healthy, then the number of these cells does not exceed 5%. If their number is exceeded, then there is a likelihood of an allergic reaction. To confirm this condition, the doctor directs the patient for the delivery of immunoglobulin E.
A blood test to detect total immunoglobulin E
Immunoglobulins are antibodies that have a detoxifying 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 a person comes into contact with an allergen.
In 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 old - up to 150;
- more than 14 years - up to 123;
- 15-60 years old - up to 113;
- more than 60 years - up to 114.
Detection of specific immunoglobulins
If with the help of previous tests it was possible to detect the presence of an allergic reaction and assume what exactly is an allergen, then a blood test for specific allergens (specific immunoglobulins G and E are detected) will help to accurately determine the source of the allergic reaction.
With this research method, blood is divided into small portions and mixed with various allergens. The number of test substances can reach 190. Next, doctors study blood samples and determine the immune response. The higher it is, the more dangerous an allergen is for a person.
How to determine an allergen by a blood test when used for the diagnosis of multiple chemiluminescence? Quite simply, since in this case special panels are used on which allergens are placed. The allergic 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.
Three types of reaction are distinguished in a blood test for allergens in adults and children:
- low - the substance does not carry any danger;
- medium - it is preferable to minimize contact with the allergen, if it is a food product, it is recommended to exclude it from the diet;
- high - allergy is caused by this substance and contact with it must be completely eliminated.
The results of a blood test for allergens are presented in the form of a long table where the patient himself will be able to examine which substances are dangerous to him.
Deciphering the analysis of immunoglobulins for an allergic reaction
Decryption and study of a blood test for allergens in adults and children takes from 2 to 3 days. In this case, the number of plasma immunoglobulins 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 higher than normal, then this is a clear sign of an allergic reaction. The allergen itself is determined during studies of its reaction with blood plasma.
Allergy Assessment Classes
To evaluate the results of the analysis, a number of classes are distinguished:
- zero (indicator below 0.35) - there is no allergic reaction, because a low amount of antibodies;
- the 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;
- the second (indicator from 0.7 to 3.5) - if the indicators practically reach 3.5, then signs characteristic of an allergic reaction may develop;
- the third (indicator from 3.5 to 17.5) - quite often the signs characteristic of an allergic reaction develop;
- the fourth (indicator from 17.5 to 50) - the blood contains a large number of antibodies, which is a clear symptom of an allergic reaction;
- fifth (indicator from 50 to 100) - this result is manifested in the case of the presence of a large number of antibodies in the human body, there is a 100% chance of an allergic reaction;
- sixth (indicator more than 100) - develops in the presence of an extremely high level of antibodies.
Methods of radio allergosorbent test
In this case, the laboratory assistant takes blood from the patient's vein. A probable allergen is added to the resulting blood sample. If the patient has intolerance to the selected allergen, then it will be possible to observe the attachment of specific antibodies to him. After this, radioactive antibodies are added. The formed radioactive complex is read using special devices.
Location
Regarding the place where to take a blood test for allergens, it can be both a public clinic (it will take a long time to wait for the results) and a private company. In the European countries and the CIS countries, the Invitro organization is very popular (the results will be received the same or the next day).
In this laboratory, a large number of immunological studies are carried out both on whole groups of widespread allergens, and on individual components. A special advantage of the organization is that it can be contacted both with a referral and on its own initiative.
Obtaining the result of the analysis is carried out both when the patient visits the clinic personally, and when entering the personal office.
Actions after detecting an allergen in the blood
Getting rid of an allergen is the most effective way to deal with an allergic reaction, but it is far from 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 treatment method has a significant drawback, which is the long duration of treatment (over several years), in addition, you need to regularly visit a doctor (every 2-3 weeks).
For symptomatic therapy, the action of which is aimed at getting rid of the negative signs inherent in allergies, antihistamines are used (Suprastin, Cetirizine, Diazolin, Diphenhydramine). 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.