**Laboratory follow-up**

Blood eosinophils provide information on current disease activity of the non-IgE-mediated type [20]. For the evaluation of disease progress and continuing disease activity and for the effective management of non-IgE-mediated allergy including NFA, blood eosinophil levels are tested repeatedly on a regular schedule.

Serum ECP should also be followed to determine changes in the disease activity of non-IgE-mediated allergy and the effectiveness of an elimination diet for food additives in atopic dermatitis.

The interpretation of the results of allergen-specific tests, such as the skin prick test and allergen-specific IgE, is often complicated because the number of positive SPT responses, the spectrum of IgE sensitisation and even the results for the same allergen often change in the same individual over time [26]. This variability may be related to the number of allergens tested and the age at which the measurements are performed. The most common food allergens determined with the SPT are soy, cow's milk, peanuts, carrot, hen's eggs whites, wheat, and corn [27].

However, changes in reactivity to allergens must be considered to be a natural phenomenon that is affected by the natural outgrowing of food allergy and the gradual acquisition of allergy to inhaled allergens, including house dust mites and pollen [2]. The change in the number of allergens to which a patient responds over time and the change in response to one allergen over time provides the physician with information on the progress of the disease. If the number of sensitised allergens decreases, the allergy itself may be regarded to be decreasing systemically. In addition, if the strength of SPT or the level of food-specific IgE is decreasing, the patient may be outgrowing the allergy.
