Allergic tests are carried out to detect an allergic disease in a person: an allergen is introduced, which takes for a potential pathogen and monitors the corresponding reaction of the organism. The diagnosis of allergy should be done only during the improvement of the condition - in two, three weeks after the man suffering from acute allergy.
Separate skin and provocative tests. Allergic skin tests allow you to assess the nature and extent of the development of inflammatory response. Conduct them by introducing an allergen into the body through the skin.
Skin allergic tests in turn are divided into qualitative and quantitative.
Qualitative allergic tests include: direct tests. Allergen is applied externally with the help of application or drops, or injected into it, scratching the skin or making a prick. Positive reaction is the appearance of a blister sample, inflammation or redness at the site. These symptoms develop in 20 minutes, after 6-12 hours or after one, two days.
Indirect tests. The allergy test is performed by administering to the healthy person a serum of blood of an infected person and an allergen (one day after serum) under the skin. A newly formed later skin reaction indicates the presence of antibodies in the patient's blood.
If a qualitative allergic test determines the presence of a person allergen sensitivity, then quantitative tests give an opportunity to evaluate the degree of this sensitivity. This method of diagnosis of allergy is also called allergenic titration, with its help you can determine the minimum concentration of allergen, which causes a visible allergic reaction.
The provocative tests are prescribed only in those cases where the result of skin allergic tests does not coincide with the previously collected allergic anamnesis. To perform such an assay, the allergen is injected into the tissue or organ that is more affected during the illness.
The following types of provocative tests are distinguished:
- Conjunctival - The allergen is digested into the conjunctival lower sac. Positive reaction is manifested in the form of itching, lacrimation and redness of the conjunctiva.
- Nazalna - a test is conducted with allergic leishmaniasis and rhinitis. In one nostril, the control fluid is burying, and in the other - the allergen. Positive is considered reaction if from the side of the nose, where the allergen was introduced, there is difficulty breathing and itching.
Inhalation. An allergic test is conducted to identify the causes of bronchial asthma: the patient inhales with an aerosol spray solution containing an allergen. If the capacity of the lungs is reduced by more than 15%, the response to the test is considered to be positive.
- Cold and heat. Such provocative allergic tests are carried out at cold, thermal urticaria, expositional. The test is carried out in the absence of clear symptoms of the disease. Its meaning is that the patient contacts the suspected allergen in the environment in which it is usually located.
- Elimination. The allergy test is based on the principle opposite to the exposure test: when a food allergy from the patient's diet is excluded, a product that is likely to cause allergy, and if the patient's everyday allergy is contained in a non-allergic ward.
- Leukocytopenic and thrombocytopenic Allergic tests. Conducted for the diagnosis of allergic medicinal and food: after the introduction of allergen monitor the level of leukocytes and platelets. It should be borne in mind that the result of the allergy test is influenced by the administration of sedative and antihistamines - they reduce the reactivity of the skin, so the use of these drugs is stopped 5-7 days before the test.