15 May 2026
Expert: Gary Falcetano, PA
Senior Manager, Global Medical & Scientific Affairs, Allergy
Thermo Fisher Scientific
Interpreting food allergy test results requires clinical context. Detectable immunoglobulin E (IgE) reflects sensitization, but does not always indicate true allergy, and misinterpretation can lead to overdiagnosis and unnecessary food avoidance.
This second Ask the Expert installment explores how specific IgE (sIgE) and component‑resolved diagnostics can improve diagnostic precision, support risk assessment for high‑risk allergens, and help clinicians manage complex presentations such as alpha‑gal syndrome.
What tools are available to help clinicians interpret sIgE blood test results, including reflex component findings?
sIgE testing can indicate sensitization, which must always be interpreted alongside clinical history. Detectable IgE does not automatically confirm clinical allergy.
Component-resolved diagnostic testing, often offered as a reflex option, provides additional clarity by identifying the proteins to which a patient is sensitized. If a whole allergen comes back positive, the components of that allergen are automatically tested to get a more granular picture of the patient’s sensitization.
Interpretation guides and report comments, when used with history and exam findings, can help clinicians determine whether avoidance, monitoring, or referral is appropriate.
How does component testing improve diagnostic accuracy and inform risk assessment, particularly for high-risk allergens (e.g., peanuts, tree nuts, sesame)?
Component-resolved diagnostics improve accuracy by identifying IgE responses to specific allergenic proteins rather than whole allergen extracts. For example, in peanut allergy, sensitization to Ara h 2 and other seed storage proteins like Ara h 1, 3, and 6 are strongly associated with true allergy and a higher risk of systemic reactions, whereas Ara h 8 is more often linked to pollen-related cross-reactivity and typically either absent or mild symptoms. Similar distinctions can be made for other foods, including tree nuts and sesame.
This level of detail allows clinicians to better distinguish true primary food allergies from cross-reactivity, such as pollen-food allergy syndrome. For primary care providers (PCPs), this leads to greater diagnostic confidence, more precise risk assessment, and clearer patient counseling. Importantly, component testing can help reduce overdiagnosis and unnecessary dietary restrictions, ultimately supporting better nutritional health and overall quality of life.
What should clinicians know about alpha-gal syndrome (AGS)?
(AGS) is a delayed IgE-mediated allergy to mammalian meat, often associated with tick exposure in the U.S., particularly from the lone star tick. The allergy results from an adverse reaction to a carbohydrate epitope found on proteins and lipids in non-primate mammals called galactose-α-1,3-galactose (alpha-gal). Some individuals develop an immune response and produce IgE antibodies to alpha-gal, and when they’re exposed again, patients with AGS may then begin exhibiting symptoms.
Symptoms typically occur 3-6 hours after ingestion and may include:
- Urticaria or angioedema
- Abdominal pain, nausea, or diarrhea
- Anaphylaxis in severe cases
Management requires careful counseling around mammalian foods and hidden sources of alpha-gal. Symptom thresholds vary, making individualized guidance and collaboration with dietitians and specialists essential.
Additional information on alpha-gal testing is available here.
How can food IgE and component testing support better outcomes in primary care?
For primary care providers managing increasing complexity within limited visit times, targeted testing with clear interpretive insights helps streamline care. When integrated with clinical history and guideline-aligned care, food IgE testing with component reflex analysis:
- Improves diagnostic precision
- Reduces unnecessary food avoidance
- Clarifies when referral is needed
- Supports confident, efficient decision-making
Labcorp’s Food IgE and component testing solutions support a more precise, patient-centered approach to food allergy diagnosis. By combining targeted allergen testing with reflex component analysis, clinicians gain deeper insight into the clinical relevance of sensitization. This approach helps reduce false positives associated with broad profile testing and supports more accurate risk assessment. In practice, it enables providers to distinguish between true allergy and cross-reactivity, minimizing unnecessary dietary restrictions and improving patient quality of life.