Allergy tests are used to confirm whether or not a suspected allergy is in the baby. There are various types, but not all of them are equally reliable
In the last twenty years, allergies have spread more and more, so much so that the percentage of allergic children in Italy has gone from 7 to 25%, in practice 1 in 4 children may have a form of allergy. Allergy is an organism reaction that occurs when our immune system mistakes a typically harmless substance (allergen) for a aggressive agent to fight.
Pollen, dust mites, milk, eggs and nuts are just some of the most common allergens among young and old that can cause more or less severe symptoms. To be sure that it is an allergy there are special ones allergy test, but they are not all the same and, above all, not all are reliable. Here then is the Prof. Viviana Moschese, Director of the Pediatric Immunopathology and Allergology Unit of the Tor Vergata Polyclinic in Rome, comes to our rescue and helps us to clarify the topic of tests for children’s allergies.
In this article
Allergies and intolerances are not the same thing
“The difference between allergies and intolerances is very important, even if there is often a lot of confusion between these two terms” says Prof. Moschese. “When we talk about allergy we mean a reaction that is immune-mediated, that is, it involves an immunological mechanism”.
What exactly does it mean? If the child is allergic to something, his body overreacts against a certain substance usually harmless for other people. This substance is called allergen. Thus, when the body first comes into contact with the allergen, the immune system produces a large amount of immunoglobulin E (IgE), a particular type of antibody. The following times those IgE antibodies specific for that allergen are activated and favor the release of inflammatory substances which cause itching, swelling, rhinitis and other typical allergy symptoms.
Allergic manifestations can be mild, with reactions limited to very severe such as anaphylactic shock (especially in the case of food allergies, drug allergies, hymenoptera venom)
In the case of intoleranceson the other hand, the immune system has very little to do with it because it is not involved. The classic example is that of lactose intolerance, now very common, in which the symptoms that the child presents depend on the lack of a particular enzyme necessary to metabolise this substance.
Allergens: which are the most common
The people responsible for allergies can be many and it is not always easy to identify them. “Allergens – explains Moschese – can be mainly of two types:
- inhalants: such as dust mites, molds and pollens from plants and trees (responsible for seasonal allergies, especially in spring);
- food: In the first two years of a child’s life, allergies to milk and egg proteins are common. Then over time other allergies such as those towards fish proteins, peanuts and nuts emerge “.
In general, the most common allergens I’m:
- dust mites;
- milk’s proteins
- egg proteins;
- fish / shellfish;
- animal hair.
When the child comes into contact with the allergen, the allergic reaction occurs which can manifest itself in various ways.
How allergies manifest themselves
Allergic manifestations can be respiratory, gastrointestinal and / or cutaneous depending on how they occur.
“The respiratory allergies can involve rhinitis, conjunctivitis, asthma, while the forms of skin allergy manifest with urticaria, itchy reactions, angioedema, atopic dermatitis. When, on the other hand, the allergic manifestation is of type gastrointestinal, typical symptoms are poor growth in children, as well as vomiting and diarrhea. In some cases it can even lead to anaphylactic shock “says Prof. Moschese.
If the child has one or more symptoms that suggest an allergy, it is advisable to speak immediately to the pediatrician who will refer the parents to a pediatric allergist.
How allergies are diagnosed
The specialist, in this case the pediatric allergist, will be able to perform specific allergy tests. “First, however, it is always necessary to carefully evaluate the entire clinical picture, starting with one thorough medical history which also includes family history. In fact, if both parents are allergic there is an increased risk that the child is also allergic. Genetic and environmental factors contribute to the onset of an allergy that must be considered in the evaluation of the allergic child, “says Moschese.
Once an allergy condition is suspected, diagnostic tests are carried out to assess whether the child has allergic sensitization. But be careful, not all existing tests are really valid.
Allergy tests are not all the same
The diagnosis of allergy makes use of some specific tests:
- the Skin Prick Test;
- the search for specific IgE against the suspected allergen (or Rast test);
- the in vivo oral trigger test (Challenge test for food allergies);
- the search for Molecular specific IgE.
These are the tests to use in those children who may have a respiratory or food allergy. “Also the total IgE dosage it can be useful, but it does not have a highly predictive value, at most it could tell us if there is a predisposition to allergic manifestations “, explains Prof. Moschese.
The Skin Prick Test