Table 3.

In vivo and in vitro tests for the diagnosis of IgE-mediated food allergies [7].

In Vivo Tests
Elimination diet	This involves an eating plan that omits a food or group of foods believed to cause an adverse reaction. By removing certain foods for a period of time and then reintroducing them during a “challenge” period, it allows the identification of which foods are causing symptoms. The elimination of 6 foods, i.e., eggs, soy, cow’s milk, wheat, seafood, and peanut/tree nuts, can be therapeutic and diagnostic in EoE.
Oral food challenge (OFC)	OFC is the gold standard for diagnosis of food allergy. It consists of administering the suspect food at established doses and observing the clinical response in a protected clinical setting.
Skin prick test (SPT)	Commercial extracts of allergen are inoculated subcutaneously to detect the presence of sIgE bound to mast cells.
Skin Prick by Prick (PbP)	PbP is similar to the SPT but is performed using fresh, cooked or raw food.
Atopy Patch Test (APT)	The suspect food is applied directly on the skin using special supports and removed after 48–72 h to study non-IgE (cell-mediated) or mixed IgE/cell-mediated responses.
In vitro Tests
Total serum IgE (tIgE)	The total concentration of IgE in the blood is measured; this is useful for assessing the presence of an allergic background but does not identify specific triggers.
Radioallergoimmunosorbent (RAST) detection of allergen-specific IgE (sIgEs)	Fluorescent enzyme-labeled antibody assay measures absolute sIgE levels. Values may correlate with the likelihood of clinical reaction for specific foods.
Component Resolved Diagnosis (CRD)	CRD is similar to RAST, but it utilizes purified native or recombinant allergens to detect sIgE antibodies against individual allergenic molecules.
Basophil Activation Test (BAT)	BAT measures by flow cytometry the expression of activation markers on the surface of basophils following the cross-linking of IgE bound to the high-affinity IgE receptor (FcεRI) by allergen or anti-IgE.