Allergic tests: definition and classification
Diagnosis of allergy using allergy test
Allergic tests were conducted to determine a person allergic disease: introduce the allergen, mistaken for a potential causative agent and monitor the body's response.
Diagnose allergy should be exclusively during improvement - two, three weeks after undergoing an acute allergic person.
Classification allergy tests
Separate the skin and provocation tests. Allergic skin tests allow to evaluate the nature and extent of the inflammatory response. Spend them by introducing an allergen into the body through the skin.
Skin allergy tests are divided in turn into qualitative and quantitative.
Qualitative allergy tests include:
- Direct sample. The allergen is applied externally via applications or drops or administered by mouth, scraping the skin or a shot. The positive reaction is the appearance of on-site sample blister, redness or inflammation. Develop these symptoms after 20 minutes, 6-12 hours, or by one, two days.
- Indirect tests. Allergy tests conducted injection under the skin healthy person serum of an infected person and an allergen (a day after the serum). Formed subsequently skin reaction indicates the presence of antibodies in the patient's blood.
If quality allergy test detects the presence of a person of sensitivity to the allergen, the quantitative tests provide an opportunity to assess the extent of this sensitivity. This method of diagnosis of allergy is called allergometricheskim titration, it can be used to determine the minimum concentration of the allergen that causes the apparent allergic reaction
Provocative tests prescribed only in cases where the result of skin allergy tests are not the same as the previously collected or allergy. To perform such tests allergen is introduced into a tissue or organ, which suffered more than others during the illness.
There are such kinds of provocative tests:
- Conjunctival - Allergies instilled into the conjunctival sac lower. A positive reaction is manifested in the form of itching, tearing and redness of the conjunctiva.
- Nasal - trial conducted in allergic rhinitis and hay fever. In one nostril control fluid was instilled, and the other - the allergen. The positive reaction is considered to be on the other side if the nose where the allergen was introduced, marked shortness of breath and itching.
- Inhalation. Allergy test is performed to determine the cause of asthma: the patient breathes with the help of the aerosol dispenser solution containing the allergen. If lung capacity will decrease by more than 15%, the response to the sample is considered positive.
- Cold and heat. Such provocative allergy tests carried out at the cold, heat urticaria,
- Exposition. The trial is conducted in the absence of clear symptoms. Its meaning is that the patient in contact with the suspected allergen in an environment in which it is normally stored.
- An elimination. Allergy test is conducted on the principle opposite exposure test: with food allergies of the patient's diet excludes foods suspected of causing the allergy, and when household allergy patients contain allergen-free room.
- Leykotsitopenicheskaya thrombocytopenic and allergy tests. Conducted for the diagnosis of drug allergy and food: after the introduction of the allergen to monitor the level of white blood cells and platelets.
Note that the result of the test for allergies affect reception sedatives and antihistamines - they reduce the reactivity of the skin, so the use of these drugs is stopped for 5-7 days prior to the test.