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Allergy tests: definition and classification

Diagnosis of an allergy by means of an allergy test

Allergy tests carry out for definition at the person of an allergic disease: enter the allergen taken for a potential disease-producing factor and monitor response of an organism.Аллергические кожные пробы

It is necessary to carry out diagnosis of an allergy only during improvement of a state – in two, three weeks after the acute allergy transferred the person.

Classification of allergy tests

Divide skin and provocative tests. Allergy skin tests allow to estimate character and extent of development of inflammatory reaction. Lead them by administration of allergen to an organism through skin.

Skin allergy tests share in turn on qualitative and quantitative.

Carry to qualitative allergy tests:

  • Direct tests. Allergen is applied outwardly by means of application or drops or entered inside, having scratched skin or having given an injection. Positive reaction emergence on site of test of a blister, an inflammation or reddening is considered. These symptoms in 20 minutes, in 6-12 hours or through one, two days develop.
  • Indirect tests. The test for an allergy is carried out by introduction under skin to the healthy person of blood serum of the infected person and allergen (in a day after serum). The skin reaction formed afterwards demonstrates existence of antibodies in the patient's blood.

If the qualitative allergy test defines existence at the person of sensitivity to allergen, then quantitative tests give the chance to estimate degree of this sensitivity. This diagnostic method of an allergy is called still allergometrichesky titration, with its help it is possible to define the minimum concentration of the allergen causing visible allergic reaction

Provocative tests are appointed only when the received result of skin allergy tests does not match collected earlier allergological anamnesis. For conducting such test allergen is entered into fabric or body which more than the others suffered during a disease.

Allocate such types of provocative tests:Аллергические пробы

  • Conjunctival – allergen is dug in in a conjunctival lower sac. Positive reaction is shown in the form of an itch, dacryagogue and reddening of a conjunctiva.
  • Nasal – test is carried out at an allergic pollinosis and rhinitis. In one nostril dig in control liquid, and in another – allergen. Reaction if from that side of a nose where allergen was entered is considered positive, the complicated breath and an itch are noted.
  • Inhalation. The allergy test is carried out for identification of the reason of development of bronchial asthma: the patient inhales the solution containing allergen by means of the aerosol sprayer. If the capacity of lungs decreases more than by 15%, reaction to test is considered positive.
  • Cold and thermal. Such provocative allergy tests carry out at cold, thermal urticaria,
  • Exposition. Test is carried out in the absence of accurate symptoms of a disease. Its sense in that the patient contacted to the suspected allergen in the environment in which it usually is.
  • Eliminative. The test for an allergy is carried out by the principle opposite to exposition test: at food allergy the product which is presumably causing an allergy is excluded from a diet of the patient, and at a household allergy of the patient contain in bezallergenny chamber.
  • Leykotsitopenichesky and thrombocytopenic allergy tests. Are carried out for diagnosis of an allergy medicinal and food: after administration of allergen watch the level of leukocytes and thrombocytes.

It is necessary to consider that the test result an allergy is influenced by reception sedative and antihistamines – they reduce reactivity of skin therefore use of these drugs is stopped in 5-7 days prior to test.

 
 
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