Introduction
There are various tests for detecting food allergy. First, however, there is always an interview and physical examination. Usually skin tests such as the prick test are common, but an examination of the blood can also provide information about a possible allergy.
Diagnosis
The most important step is to first identify the right allergen as the trigger. Diagnosis often begins at home, as parents often quickly suspect certain foods as triggers. If the above-mentioned symptoms occur, omitting the suspected food can confirm the suspicion if it leads to the disappearance of the symptoms.
Subsequently, a reaction can be provoked by small amounts of the food. If, for example, hives appears, the presence of an allergy to this food is very likely. However, if only gastrointestinal symptoms occur, food intolerance cannot be delimited and thus cannot be excluded.
A similar procedure or even the keeping of a complaints diary, which puts food and symptoms into a temporal context, is often recommended by doctors, since the investigation of all possible and conceivable allergens is time-consuming and usually unnecessary. If the suspicion of some allergens has narrowed, a so-called prick test is usually suitable for further diagnostics. Here, the skin on the forearm or back is first divided into fields with a pencil.
On each of these fields a serum is applied, which contains a concentrated amount of a certain allergen. This liquid is then placed under the skin with a tiny needle so that the immune system can access it. If the body is sensitized, i.e. allergic, to this allergen, a visible and reddened lump will form there after about twenty minutes, as the allergic reaction as described above causes water to enter the tissue and cause swelling.
This test is very safe and meaningful, especially for children. Not only can a statement be made as to whether a food allergy exists, but the size of the lump can also be used to assess the severity of the allergy. In addition, a blood test, the so-called RAST, is possible, which measures the amount of antibodies in the blood that are formed against the respective allergen. However, the value measured here does not necessarily indicate the severity of the disease. In addition, it happens again and again that the test is negative despite the existence of an allergy with corresponding symptoms.
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