Wheat allergy (WA)
Practical guide to the diagnosis of wheat allergy
Symptom diary, IgE antibody test and skin prick test, as well as oral food provocation - these are the possible recommendations for diagnosing a wheat allergy. It is important to exclude celiac disease beforehand. If all wheat allergy tests remain negative, gluten / wheat sensitivity may be present.
Who should be tested for wheat allergy in practice?
If patients develop clinical symptoms after eating wheat or foods containing wheat, various gluten- and grain-related disorders (GRDs) may be the cause. If the autoimmune disease celiac disease has been reliably ruled out, a wheat allergy test can be recommended as the next step
What do guidelines on wheat allergy diagnostics recommend?
Before a wheat allergy test is carried out in practice, it is important to reliably rule out celiac disease. According to the current guidelines of the European Academy of Allergy and Clinical Immunology (EAACI), the steps recommended for a wheat allergy diagnosis are the same as for other allergies: Firstly, the symptoms should be recorded in a symptom diary as part of the medical history. This is followed by the determination of wheat-specific IgE antibodies in the serum and/or via a skin prick test using wheat proteins Finally, provided there is no history of immediate onset respiratory symptoms, an oral food challenge may be used to confirm the diagnosis of wheat allergy.
The 3 steps of wheat allergy diagnostics:
- medical history, including complaint diary
- skin prick test and/or serum test for specific IgE
- oral food provocation for confirmation
Key questions for the detectionof wheat allergy
According to the EAACI guideline, the following key questions should be asked as part of the diagnosis process.
- At what age did the manifestations begin?
- What symptoms occurred where - and with what intensity?
- Did the symptoms appear immediately, did they subside spontaneously?
- What were previous reactions treated with - and how successfully?
- Are there any suspicious foods and if so, which ones?
- How much of the food triggers symptoms and does it happen every time?
- Has the food been swallowed, touched or inhaled?
- Are there other allergies with potential for cross-reactivity?
- What does the typical diet look like - and is it appropriate?
- Which foods are avoided and for what reason?
- Is there a history of atopic or allergic diseases?
Validity of wheat IgE and skin prick tests is limited
Specific IgE tests are available for several wheat allergens.. There are also tests for wheat dependent exercise induced anaphylaxis (WDEIA): The heat-stable omega 5 gliadin is available as a recombinant allergen. However, as with other food intolerances, IgE tests are only of limited diagnostic value. For example, the presence of specific serum IgE for wheat without clear symptoms is not diagnostic: many people nevertheless tolerate wheat exposure - especially those with sensitivity to grass pollen. Even in small children with atopic dermatitis, the specific IgE test often shows high values and yet wheat is well tolerated. A positive specific IgE antibody test or wheat prick test therefore supports the assumption that the symptoms are due to a wheat allergy - but does not prove the diagnosis of wheat allergy. Conversely, a negative test does not rule out a diagnosis of wheat allergy.
Special case of wheat-induced eosinophilic esophagitis
Wheat-induced eosinophilic esophagitis (EoE) is diagnosed by the presence of at least 15 eos/hpf in an esophageal biopsy taken during esophagogastroduodenoscopy (EGD). IgE measurement by skin prick test or specific serum tests have a low sensitivity and specificity for wheat-induced reactions. The gold standard for the evaluation of wheat in EoE pathogenesis is an eight-week elimination diet followed by EGD, whereby a biopsy showing eosinophilic inflammation with 30 eos/hpf in the stomach and 50 eos/hpf in the duodenum can confirm a positive diagnosis.
Wheat allergy diagnosis confirmed by oral food challenge
Following the IgE-based wheat allergy tests, a supervised oral food challenge is recommended to confirm or exclude the wheat allergy diagnosis. The gold standard is a positive, double-blind, placebo-controlled, oral food challenge after improvement of the symptoms under strict allergen avoidance (oral food challenge should be omitted if there is a history of severe immediate or life-threatening reactions and a positive specific IgE).
What is the diagnostic procedure if wheat allergy is excluded?
If neither celiac disease nor a wheat allergy can be diagnosed, but the symptoms improve after abstaining from wheat, a gluten / wheat sensitivity should also be clarified diagnostically. However, a wheat allergy must also be differentiated from other allergies. In addition to other cereal allergies, this also includes a soy allergy, as bread and baked goods often contain soy
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Read moreSources
- Preda M, Popescu FD, Vassilopoulou E, Smolinska S. Allergenic Biomarkers in the Molecular Diagnosis of IgE-Mediated Wheat Allergy. Int J Mol Sci. 2024;25(15):8210. published 2024 Jul 27. doi:10.3390/ijms25158210
- Riggioni C, Ricci C, Moya B, et al. Systematic review and meta-analyses on the accuracy of diagnostic tests for IgE-mediated food allergy. Allergy. 2024;79(2):324-352. doi:10.1111/all.15939
- Santos AF, Riggioni C, Agache I, et al. EAACI guidelines on the diagnosis of IgE-mediated food allergy. Allergy. 2023;78(12):3057-3076. doi:10.1111/all.15902