allergy testing

allergy testing


 Diagnostic tests for allergy, what are they?



We tell you what tests for allergy exist and when we should ask them to do them.

Sara P. Lorenzo

The allergy is a failure of our immune system in which a substance in principle harmless to us (called allergen) produces a reaction of hypersensitivity. Our body identifies that substance as an invader so our antibodies (responsible for defending us) join it. In doing so, a substance called histamine is released that is anti-inflammatory. Under normal conditions histamine would flow through our body to eliminate substances detected as harmful. However, if there is nothing to fight, histamine joins our muscles and tissues producing inflammation in the part where it was released.

Allergy tests are performed with the aim of detecting a possible allergy in the person and give a reliable diagnosis. It is said that there are as many allergies as there are substances in the world. It may happen that we experience symptoms that we believe are normal but are actually caused by an allergy that we did not know about. For example, asthma attacks or eczema on our skin can have an allergic cause.
When should we request allergy tests?

Whenever we suspect that we have an allergy. In this sense, our body will send signals to the substance in question. That is, we will have an allergic reaction. The symptoms we show depend on the allergen and the person. However, the most common are:

- Allergic rhinitis: symptoms such as runny nose, sneezing, congestion and itching are manifested. Sometimes patients can confuse it with a permanent cold. Depending on the intensity of the symptoms during the year, it may be seasonal rhinitis (when the symptoms worsen in the pollination phase of the plants) or chronic or perennial rhinitis (when the intensity remains constant throughout the year).

- Eczema or urticaria: the skin is affected. There is itching, inflammation, redness, crusting and lifting of the skin in the form of scales.

- Bronchial asthma: those affected are the bronchi. An obstruction occurs, an inflammation that is reversible. Frequently it comes together with a cough, a feeling of tightness in the chest and whistling when breathing.

- Allergic conjunctivitis: the eyes swell, itch, cry, sting and the person presents photosensitivity.

Also keep in mind that allergies often tend to have a hereditary base. This means that if your parents have allergies it is likely that you also develop one, but it does not have to be exactly the same, what we inherit is rather the predisposition to have one. In this case, we would also have to consider testing the allergy.

The allergist will perform a scan of the nose and ears to make a diagnosis
The allergist will perform a scan of the nose and ears to make a diagnosis

Allergy tests

If you suspect a possible allergy, tell your doctor to refer you to an allergist. It is a doctor specialized in allergies that will pass the necessary tests in order to establish a diagnosis. The most commons are:

- Questions about your medical history: apart from the basic data of the patient questions about possible family history are made, the times of the year where it is more common the appearance of allergic reactions, the frequency and intensity of the symptoms, possible allergens, location of the residence, characteristics of the house ...

- Exploration: the doctor will explore your skin in search of possible affected areas. It will also explore your nose (rhinoscopy) and ears (otoscopy). Finally, measure your "peak expiratory flow" which is the speed at which we expel air through the nose and a cardiopulmonary auscultation to check for bronchial asthma.

- Skin tests: in order to detect environmental allergies and some food. They are the most common and consist of inoculating small amounts of the allergen in question. They are reliable and safe. The application is usually on the back and forearm. There are several ways.

- Puncture: a minimum amount of allergen is placed on the skin and punctured lightly.

- Intradermal reaction: here the allergen is directly introduced into the skin and the results are observed.

- Patch test or patch tests: apply when you want to study a specific allergen. A patch is placed on the skin (usually on the back) with the substance to be checked for two days. Then the reaction is observed.

This type of test is ideal for environmental allergies, but it is not clear if the person is allergic to certain foods. To be 100% sure the allergist has to make sure by a blood test. It allows us to quantify the antigens that we have in circulation, they will give us information about the type of allergy and severity. If the food is positive in both tests we can affirm the allergy.

- Proof of challenge: they apply when the previous tests have not been clear or have given negative results, however there is still suspicion. In these cases the patient is put in contact with the allergens progressively (both environmental and pharmacological allergens) and the reactions are carefully observed. In principle this test is left as the last option for food allergies because they can produce very intense reactions in some people. For example, anaphylactic shock can occur and the life of the person is endangered. This allergic reaction is fatal if it is not controlled in time. The provocation must always be carried out in a consultation prepared with the necessary medication and the appropriate professionals in case of complications.
Waiting for a diagnosis

Once the tests are done, the responsible doctor will give us the results. A negative result indicates that we are not allergicto the substance. On the contrary, the diagnosis will be positive when we react allergically to the substance.There are times when the person can give a negative result to the substance and remain allergic. Or what happensotherwise, people who test positive for skin tests but who have not experienced allergic reactions with thatsubstance in your life. That is why it is important that the responsible physician assess the results as a whole.In this way, you can make a good diagnosis and suggest the changes that the patient has to make in his style oflife to avoid the allergen and possible consequences.