Methods of diagnosing allergies

Successful treatment and prevention of allergic reactions largely depend on identifying the underlying cause, which can be quite difficult to do.

Firstly, the difficulty of detecting primary factors causing allergies may be due to cross-reactions. Secondly, if there is a suspicion of "pseudoallergy", it is necessary to conduct a more thorough examination of the internal systems of the body - digestive, endocrine, lymphatic and immune. If no metabolic disorders or signs of chronic infections are detected, then an important task is a comprehensive study of the state of the immune system and allergy diagnostics.

Based on a thorough examination of the body and determination of the cause of the allergy, individual therapy is selected that leads to recovery.

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Available tests for allergic reactions are divided into:

• conducted with the participation of humans (in vivo) – tests on the skin, mucous membranes, sublingual area;
• contactless technologies based on determining the reaction of blood serum when interacting with an allergen (in vitro).

The most accessible and widespread method of diagnosing allergies is a skin test. Among the advantages of this testing are its clarity and low cost.

Allergy diagnostic methods include provocative testing – the introduction of a suspected pathogen into the body in small portions.

The condition of the elimination method is the discontinuation of the drug or the exclusion of the allergen product from the diet.

A relatively new allergy diagnostic method is the Voll method. Bioresonance research is carried out on special equipment, with the help of which information is read from biologically active points. The method produces reliable results, provided that testing is carried out by a qualified specialist.

It should be noted that the data from any allergy diagnostics are considered reliable for six months from the date of the study.

Diagnosis of allergies in children

In order to study the course of allergic diseases in children and to develop treatment plans, a number of special tests are carried out.

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Skin test method

Diagnosis of allergies in children by allergy testing is widely used to establish sensitivity to an allergen. Skin testing with a set of allergens can be in the form of: a prick (prick test), a scratch (scarification method) and an intradermal test.

Indications for the study are allergic reactions of food, respiratory, and medicinal origin, as well as atopic dermatitis and bronchial asthma.

The test is not performed if:

• there is an exacerbation of an existing allergy or other chronic disease;
• the baby has contracted an infection (flu, acute respiratory viral infection, etc.);
• the condition is quite serious;
• For treatment purposes, drugs containing hormones (corticosteroids) were used.

At the beginning of the diagnostic examination, a consultation with a pediatrician and laboratory reports are required - urine analysis, as well as a general blood test and a biochemical blood test.

The skin testing kit includes the most common allergens: food, animal epithelial particles, wool, fluff, plant pollen, house dust, and others. The skin test is performed on the inner surface of the forearm (at a distance of 3 cm above the wrist area). If the skin of the subject has allergic signs, then unaffected areas (for example, the back) are tested.

Allergy tests are prohibited for children under five years of age. The formation of the immune system at this age is usually not complete and this is fraught with a number of complications, including chronic diseases. The procedure itself is painful.

During the testing process, an allergen is applied to the injection/scratch area, after which swelling and redness of the skin may appear. Such a reaction will indicate the presence of an allergy. The test results are checked after 24 or 48 hours under the obligatory condition of bright lighting. If the skin rash element is more than 2 mm in diameter, the test is considered positive. Up to 20 allergens are checked during one diagnostic.

Before conducting an allergy diagnosis, it is important to stop taking anti-allergy medications, otherwise the tests are considered erroneous.

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Method for determining groups of specific Ig E antibodies

Diagnosis of allergies in children under five years of age involves taking venous blood to detect specific immunoglobulins. This technology allows for the assessment of more than 200 allergens and helps to accurately determine the cause of the disease. The method has no contraindications, since there is no contact of the patient's body with the tested pathogen. The presence of allergies is determined by the reactions of the blood serum during interaction with the allergen.

Indications for conducting the study are not only allergic manifestations themselves. Using this method, it is possible to assess the risk of allergies in children in whose family such pathologies are noted.

It is recommended to reduce physical and mental stress several days before allergy diagnostics.

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Method for detection of specific IgG

This diagnostic is used for food allergies in children. The list of allergenic products includes the most common fruits, vegetables, cheeses, fish and poultry, dairy products, nuts, etc.

The material for the study is blood serum.

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Diagnosis of food allergies

The study of food allergic reactions is carried out using the following methods:

• allergy tests;
• non-contact methods (using blood serum);
• provocation;
• with the help of diets.

Regarding skin tests as a method of allergy diagnostics, doctors' opinions are divided. Some of them completely reject this method in the case of food allergies, while others select an elimination diet based on the results of the skin test.

The testing technology is based on a scarification test, when a suspected allergen diluted in a certain proportion is applied to the scratch/prick area of the forearm.

Diagnosis of food allergy by serum reaction depends, as with skin testing, on the quality of the allergen (quantitative dose in the test mixture). These methods are aimed at detecting IgG, IgE and IgM antibodies. The problems of the study are the instability of allergens and possible cross-reactions. It is difficult to interpret positive results in cases of delayed or chronic reactions, rather than in acute reactions.

Food provocations are carried out under full medical supervision. Various products, including the suspected allergen, are placed by a third-party medical worker in special capsules (so that neither the doctor nor the patient can guess the contents). The allergen product can be masked by other food. The essence of the method is that by the occurrence of a reaction only to the allergen, a positive result in the diagnosis of allergy can be concluded.

Patients with severe food allergies are not subjected to the food challenge method to avoid serious consequences.

A food diary very often brings clarity and helps to track the relationship between foods and the manifestation of an allergic reaction.

Allergy diagnostics are also carried out by an elimination diet, in which the suspected allergen is completely excluded from the diet. If after this the symptoms disappear, then the diagnosis is food allergy.

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Diagnosis of drug allergy

The process of questioning the patient and subsequent analysis of the allergic anamnesis to drugs most often allows the correct diagnosis to be established.

Criteria for drug allergic reaction:

• clinical manifestations are associated with drug intake;
• there is significant relief or complete elimination of symptoms associated with discontinuation of the drug;
• allergic-like manifestations of toxic, pharmacological nature and other side effects are excluded;
• the presence of a latent sensitizing period in the case of the first administration of the substance.

Laboratory diagnostics of drug allergies, as well as provocative tests, are used if a detailed study of the anamnesis does not help to identify the allergen.

To determine the drug allergen, the following laboratory tests are used:

• enzyme immunoassay – developed for a relatively small group of pharmacological drugs, including: gentamicin, a number of beta-lactam antibiotics, lidocaine, acetylsalicylic acid. Testing is possible by taking 1 ml of blood serum from the patient. The duration of the study is up to 18 hours;
• Shelley testing - more suitable for scientific experiments that require specially trained personnel;
• Fluorescent allergy diagnostics has been developed for antibiotics, non-steroidal anti-inflammatory drugs, anesthetics, a number of vitamins, etc. The test lasts about half an hour, and 1 ml of blood is enough to test ten medications;
• Natural leukocyte emigration inhibition test (NLEIT) – has been known for over 30 years, and is used for antibiotics, local anesthetics, sulfonamides, and a number of nonsteroidal anti-inflammatory drugs. It takes an hour and a half to obtain the result. Disadvantages of the method – it is not used to examine children under 5 years of age, patients with oral inflammation, or in acute allergic processes.

Skin tests for the purpose of diagnosing drug allergies are not widely used, since the reliability of the results does not exceed 60%. The scarification method and prick test have been developed only for a number of beta-lactam antibiotics. The use of these methods is unacceptable in patients with severe allergies (Quincke's edema, anaphylaxis, etc.).

Application methods are the most informative way to diagnose allergies in contact dermatitis. The test is carried out on skin moistened with saline (the area between the shoulder blades) provided that there are no allergic manifestations on it. A chamber with the suspected allergen drug is attached to a patch in this area, which comes into contact with the skin. After twenty minutes, the presence of an instant reaction is checked; if none is detected, the bandage is left for up to 72 hours.

Provocative testing is rarely used when the results of a thorough medical history and laboratory data have not established a relationship between clinical manifestations and the drug, and it is not possible to cancel the drug. Such testing is carried out strictly under the supervision of a specialist in conditions of resuscitation readiness.

Contraindications for provocative testing:

• period of exacerbation of allergies;
• previous history of anaphylaxis;
• severe diseases of the endocrine and cardiac systems, as well as liver and kidney diseases;
• pregnancy;
• age up to 5 years.

Allergy provocation diagnostics for medications in tablets is performed by a sublingual test, when a quarter of the tablet substance is placed under the patient's tongue (drops can be tested by applying them to sugar). Itching in the oral cavity, swelling, redness after a short period of time will indicate a positive result and the presence of an allergy.

Another provocative method is the dosed introduction of the suspected allergen (starting with small doses) subcutaneously and determining the reaction after half an hour.

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Laboratory diagnostics of allergies

Laboratory diagnostics of allergies is the most relevant method, including:

• radioallergosorbent testing to detect specific immunoglobulin classes E, M, G, carried out on the basis of blood serum;
• enzyme immunoassay technology for detecting specific immunoglobulin classes E, M, G using the blood serum of the test subject;
• study of changes in blood serum basophils during contact with an allergen or the Shealy method (determines only the state of sensitization itself);
• reactions from blast transformation/inhibition of leukocyte migration.

Enzyme immunoassay has a number of disadvantages:

• low sensitivity of the test (i.e. there is an allergy, but the diagnostics do not detect it);
• on the contrary, high sensitivity with low specificity, which leads to a false positive reaction (as a result of testing, an allergy is detected, but in fact it is not there).

Laboratory diagnostics of allergies is indispensable in the following situations:

• active skin lesions (eczema, atopic dermatitis, etc.);
• increased allergic reaction of the skin, which leads to false positive or false negative conclusions (with Quincke's edema, mastocytosis, etc.);
• it is impossible to apply the skin testing method as a result of the constant use of antiallergic drugs;
• when testing children and the elderly, skin test results may be unreliable due to changes in the reactivity of the skin (different degrees of reaction to the irritant);
• if an anaphylactic reaction or conditions predicting one have been previously observed.

The advantages of laboratory allergy diagnostics include:

• safety due to the absence of contact between the allergen and the patient’s body;
• conducting research at any stage of disease development;
• a one-time blood test allows you to test sensitivity to a large number of allergens;
• The results of allergy diagnostics are presented in the form of quantitative and semi-quantitative indicators, which helps to conduct a reliable assessment of the degree of sensitivity to the allergen.

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Computer diagnostics of allergies

Computer diagnostics of allergies using the Voll method has become widely used.

This testing collects information about the frequency of electrical oscillations at the cellular level. Nerve endings control the work of the entire organism by means of electrical signals coming into the central nervous system. The Voll method is based on recording the data of the information flow.

Results on the state of the body's systems are read from electropuncture points. The technology allows for reliable determination of functional changes and selection of a suitable medicine for each patient through individual testing. The accuracy of allergy diagnostics reaches 99% if it is performed by a qualified physician.

Science is in constant motion, resulting in the emergence of devices for allergy diagnostics. The Swiss company "Phadia" has developed the "ImmunoCap" system, characterized by high accuracy and quality of results. Among the test kits, there are absolutely unique ones that allow with 100% reliability to identify the presence of allergies in children and adults. The diagnostic complex includes systems for determining sensitivity to pollen, household dust, mold, as well as methods for identifying cross-reactions.

Japanese quality means accuracy and reliability. The automatic analyzer "CLA-1 TM Hitachi" is indispensable for carrying out the method of multiple chemiluminescence (MAST). Modern and particularly sensitive technology helps to reliably determine allergen-specific antibodies in blood serum. Among the advantages of the device are: reliability, ease of use, the ability to diagnose cross, hidden and polyvalent allergies.

Allergy diagnostics should include a comprehensive approach, which begins with a consultation with an allergist. The patient should remember all the details of the disease development, indicate the supposed provoking factors, it is important to talk about similar problems in close relatives. The doctor will definitely ask about living conditions, organization of the workplace, etc. Only after a preliminary conversation will the allergist prescribe a diagnostic method.

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