From the Guidelines
To diagnose a wheat (Celiac) allergy or flour (Triticum aestivum) hypersensitivity, a detailed medical history focusing on symptom patterns after flour exposure should be taken, followed by skin prick testing or specific IgE blood tests to identify the allergic reaction, and if necessary, an oral food challenge under medical supervision. The diagnostic process for wheat or flour allergy involves several steps, including:
- A thorough medical history to identify symptom patterns after flour exposure
- Skin prick testing (SPT) or specific IgE blood tests to assess for immediate/type I hypersensitivity reactions 1
- An elimination diet where flour products are removed for 2-4 weeks and then gradually reintroduced while monitoring symptoms to confirm the diagnosis
- Oral food challenge (OFC) under medical supervision, which is the criterion standard for diagnosis, where increasing amounts of flour are consumed while watching for reactions 2 Common symptoms of flour allergy include hives, itching, nasal congestion, digestive issues, and in severe cases, anaphylaxis requiring immediate epinephrine. If diagnosed with a flour allergy, strict avoidance is necessary, which means carefully reading food labels for wheat, gluten, and other grain ingredients. Consider consulting with a dietitian to ensure nutritional needs are met while avoiding flour products. Flour allergies involve an immune system response where the body mistakenly identifies proteins in wheat or other grains as harmful, triggering the release of histamine and other chemicals that cause allergic symptoms. The National Institute of Allergy and Infectious Diseases (NIAID) Food Allergy Expert Panel suggests consideration of limited food allergy testing, including wheat, if a child less than 5 years of age has moderate to severe atopic dermatitis and persistent disease despite optimized management 1. In recent years, atopy patch tests (APT) have been introduced to assess for type IV hypersensitivity/eczematous reactions, but their use is not recommended for routine diagnosis due to conflicting findings and difficulties in interpretation 1. Component-resolved diagnostics, such as measuring IgE to specific food allergen components, are becoming increasingly used to confirm certain food allergies, but their limited global availability and technical laboratory requirements render them of limited utility in many clinical contexts 2.
From the Research
Diagnostic Criteria for Wheat Allergy or Flour Hypersensitivity
The diagnostic criteria for wheat allergy or flour hypersensitivity involve a combination of clinical history, physical examination, and diagnostic tests. The following are some of the key diagnostic criteria:
- Clinical history: A thorough clinical history is essential to diagnose wheat allergy or flour hypersensitivity. This includes a detailed account of the patient's symptoms, medical history, and dietary habits 3.
- Diagnostic tests: Several diagnostic tests are available to diagnose wheat allergy or flour hypersensitivity, including: + Skin prick tests (SPTs): SPTs are commonly used to diagnose allergies, including wheat allergy. However, they may not be as sensitive as other tests, such as ImmunoCAP 4. + ImmunoCAP: ImmunoCAP is a laboratory test that measures the levels of specific IgE antibodies in the blood. It is a more sensitive test than SPTs and can be used to diagnose wheat allergy 4. + Patch tests: Patch tests can be used to diagnose delayed-onset reactions to wheat, such as atopic eczema. However, they may have a lower specificity than other tests 5. + Oral food challenge: An oral food challenge is considered the gold standard for diagnosing food allergies, including wheat allergy. However, it should only be performed under medical supervision 3, 6.
- Laboratory tests: Laboratory tests, such as measurement of wheat-specific IgE antibodies, can be used to support the diagnosis of wheat allergy or flour hypersensitivity 4, 7, 5.
Diagnostic Challenges
Diagnosing wheat allergy or flour hypersensitivity can be challenging due to the complexity of the allergenic composition of wheat flour. The use of fractions, such as water/salt soluble fraction, native gluten fractions, and wheat isolate fraction, can help to improve the diagnostic accuracy 7. Additionally, the ladder approach can be used to reintroduce allergens in children with non-IgE mediated gastrointestinal food allergy, including wheat allergy 6.
Key Findings
Some key findings from the studies include:
- ImmunoCAP is a more sensitive test than SPTs for diagnosing wheat allergy 4.
- Patch tests can be used to diagnose delayed-onset reactions to wheat, but may have a lower specificity than other tests 5.
- The ladder approach can be used to reintroduce allergens in children with non-IgE mediated gastrointestinal food allergy, including wheat allergy 6.
- The use of fractions, such as water/salt soluble fraction, native gluten fractions, and wheat isolate fraction, can help to improve the diagnostic accuracy of wheat allergy 7.