A central component of the workup of eosinophilic esophagitis (EE or EoE) is the allergy evaluation. A number of studies have demonstrated that allergies when children with EE who have been placed on a diet of only a hypoallergenic elemental formula, in almost all cases they have rapid resolution of their symptoms, and normalization of their esophageal biopsies . This indicates that food allergies appear to be the main cause of this disease.
Although elemental formula diets are highly effective, they can be quite challenging to stay on, so the role of the allergist is to try to identify which food allergens may be triggering a patient’s disease so that they can be removed from the diet. There are 3 main ways in which food allergies can be detected in EE.
– Skin prick testing
– Blood allergy testing (eg. RAST)
– Atopy patch testing
The first two types of allergy tests are used most commonly to look for food allergies that have caused an allergic reaction such as hives, wheezing, or anaphylaxis. They have also been used to evaluate for environmental allergies which may be triggering asthma or hay fever symptoms. Skin testing and RAST testing have in common that they detect IgE mediated allergies, that is allergic reactions that are caused by this allergy antibody typically associated with immediate-type reactions.
However, there is another allergy pathway that is also considered to be involved in the development of eosinophilic esophagitis, that is a delayed type allergies. This type of allergy is mediated by allergy cells, rather the allergy protein IgE. Because IgE is not involved, skin testing or RAST tests cannot detect allergies caused by this mechanism. For this reason, another type of test has been used to look for delayed-type allergies, the atopy patch test . Patch testing is still considered a research test since the validity of this test in identifying food allergens in EE has not been established. However, many major centers which treat Eosinophilic Gastrointestinal Diseases have patch testing available to be performed as part of their diagnostic evaluation.
After the allergy workup has been completed, dietary therapy options for EE should be discussed with their allergist. The drawback regarding allergy testing is that it is not 100% accurate. For eosinophilic esophagitis in particular, there often are false positive and negative results from any of the above testing methods. Because of these inaccuracies with testing, the centrol role of allergies in EE, and the overall complexitiy of this disease, it is important to have an allergist who is experienced in eosinophilic esophagitis diagnosis and treatment as a member of the medical team. Their dietary guidance and knowledge may provide significant assistance towards resolution of this disease.