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Food Allergy

Guidelines advise that diagnosis of food allergy starts with a physical examination and a food allergy-focused patient history1,2 in combination with diagnostic testing.3-5 An allergy-focused clinical history should be tailored to the presenting symptoms and age of the patient.2

Food allergy can be classified into IgE-mediated and non-IgE-mediated allergy. IgE-mediated reactions are acute and frequently have a rapid onset while non-IgE-mediated reactions are generally characterized by delayed and non-acute reactions.6

Guided by the allergy-focused patient history, work through the most appropriate next steps, including considerations for specific IgE tests—when added to an allergy-focused patient history, the use of skin-prick tests (SPT), serological tests, or both increases your confidence in diagnosis and clinical management by ruling in or ruling out allergies7,8

Guided by the allergy-focused patient history, work through the most appropriate next steps, including considerations for specific IgE tests—skin-prick tests (SPT), specific IgE blood tests, or both—as diagnostic tools.
Key Allergy Test Differences Specific IgE blood testing Skin prick testing
Typically ordered and reviewed by a clinician YES YES
Patients do not need to discontinue allergy medications YES NO
Requires only one needle stick (a single blood sample) YES NO
Carries no risk of severe allergic reaction YES NO
Can be used when extensive skin rash is present YES NO
Can be used for children as young as 3 months of age YES YES
Component testing is available
 YES NO
Same day results in office NO YES

Common food Allergies

Eight allergens account for 90% of food allergies in children/young people.10,11

Asthma Symptoms

Milk

wheat

Wheat

Peanut

Peanuts

Shellfish

Shellfish

Fish

Fish

Soy

Soy

Tree nut

Tree Nuts

Asthma Symptoms

Egg

Who should be tested

If an allergy-focused clinical history suggests an IgE-mediated food allergy, SPT or specific IgE blood tests are needed to help confirm the diagnosis. A positive test on its own simply shows sensitization to a food allergen and is not itself diagnostic of food allergy.

Correct diagnosis of food allergy, followed by education and advice based on valid test results may help to reduce the incidence of adverse reactions resulting from true food allergies, and may also help to reduce the unnecessary dietary exclusion of foods that are safe and should be eaten as part of a normal, healthy diet.2

 

Patient presents with symptoms suggesting a food allergy

Allergy-focused patient history is taken

IgE - mediated

Allergy test for suspected
allergens

Only 1 ml of blood is required for the
main food allergen

Allergy management plan


Adapted from NICE Guideline CG1162

Non IgE - mediated

Consider an exclusion/re-introduction diet
consultation with a dietician

Consider an exclusion/re-introduction,
diagnosis is confirmed

Allergy management plan


Adapted from NICE Guideline CG1162

Allergen Testing

Whole Allergens

ImmunoCAPTM Whole Allergen testing provides an objective measurement of the circulating specific IgE antibodies and the sensitization to a specific whole allergen. Specific IgE antibodies can appear as a result of exposure to an allergen in atopic individuals. ImmunoCAP Whole Allergen measure IgE antibodies to specific allergens in human serum or plasma and allows quantitative measurements of a wide range of individual allergens. Over 550 different allergens are available for determinations.11

Allergen Components

Often, allergies are not as clearcut as a simple “yes” or “no.” That’s where specific IgE blood testing for allergen components comes in. ImmunoCAPTM Allergen Components measure specific IgE antibodies to individual molecular allergens in serum or plasma. These allergens, which are purified or recombinant proteins, offer the unique opportunity to assess a person’s allergic sensitization pattern at the molecular level. Different component groups often elicit different types of reactions, so testing them can indicate if a patient’s positive test results were caused by allergy to a given substance or by a cross-reaction with another allergen. Specifically for peanuts and tree nuts; measuring specific IgE for allergen components helps the clinician weigh a patients risk of a systemic reaction versus a more mild or localized response.12

More than 100 different ImmunoCAP allergen components are available for determinations,11 including:


MILK

  • Bos d 4 (alpha-lactalbumin)
  • Bos d 5 (beta-lactoglobulin)
  • Bos d 8 (casein


EGG

  • Gal d 1 (ovomucoid)
  • Gal d 2 (ovalbumin)
     


PEANUT

  • Ara h 1, 2, 3, 6 (storage proteins)
  • Ara h 8 (PR-10 protein)
  • Ara h 9 (lipid transfer protein)
  • Bet v 2 (profilin)
  • MUXF 3 (CCD)

 

 

 


TREE NUTS

Hazelnut:
  • Cor a 1 (PR-10 protein)
  • Cor a 8 (lipid transfer protein)
  • Cor a 9, 14 (storage proteins)
Walnut:
  • Jug r 1 (storage protein)
  • Jug r 3 (lipid transfer protein)
Brazil Nut:
  • Ber e 1 (storage protein)
Cashew:
  • Ana o 3 (storage protein)


The presence of allergen-specific IgE is usually a risk of allergy symptoms and a result ≥0.1 kUA/L indicates sensitization. Traditionally, the higher the IgE level the greater the risk.

Clear results are easy to interpret and explain to patients

The higher the concentration of lgE antibodies, the higher the risk for symptomatic allergy16

Chart reference 15
 

Guided by the IgE-mediated test result, an individual plan to manage and treat the allergy can be tailored in conjunction with a dietitian, in order to achieve improved quality of life and overall well-being.

Interpretation of test results

Results should be read in conjunction with the clinical history.13 

The Power of Knowing

The result of IgE-mediated tests can help to confirm a suspicion of allergy, determine the offending allergens, or to rule out allergy altogether. Ruling out allergy can be as important as confirming it. If allergy is ruled out as the cause of the symptoms, you may reduce worry and unnecessary food avoidance or medication.

  • Food allergy is self-reported 6 times more often than its actual prevalence, causing unnecessary worry and avoidance of food14
  • Gastrointestinal (GI) symptoms caused by food intolerance, lactose intolerance, Celiac Disease (CD), or Irritable Bowel Syndrome (IBS) are often confused with food allergy11,15

You can also continue to search for other causes. Test results provide precise and reliable answers to a patient’s allergy profile which may help you discover hidden risks, such as allergies due to cross-reactions.

Allergy Testing

Conditions & Diseases

Understand allergic and autoimmune diseases.

Learn more
References
  1. Pawankar R, at el. World Allergy Organization. White Book on Allergy (WAO). 2011. http://www.worldallergy.org/UserFiles/file/WAO-White-Book-on-Allergy_web.pdf. Accessed December 2017.
  2. National Institute for Health and Care Excellence. Food allergy in children and young people (CG116). 2011. London: National Institute for Health and Care Excellence.https://www.nice.org.uk/guidance/cg116/resources/cg116-food-allergy-in-children-and-young-people-full-guideline3. Accessed December 2017.
  3. Walsh J, O'Flynn N. Diagnosis and assessment of food allergy in children and young people in primary care and community settings: NICE clinical guideline. Br J Gen Pract. 2011;61(588):473-475.
  4. Muraro A, et al. EAACI food allergy and anaphylaxis guidelines: diagnosis and management of food allergy. Allergy. 2014;69:1008-1025.
  5. Boyce JA, et al. Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of the NIAID-Sponsored Expert Panel. J Allergy Clin Immunol. 2010;126:S1-58.
  6. Spergel JM. Nonimmunoglobulin E-Mediated Immune Reactions to Foods. Allergy Asthma Clin Immunol. 2006 2:78
  7. Duran-Tauleria E, Vignati G, Guedan MJ, et al. The utility of specific immunoglobulin E measurements in primary care. Allergy. 2004;59 (Suppl 78):35-41.
  8. Niggemann B, Nilsson M, Friedrichs F. Paediatric allergy diagnosis in primary care is improved by invitro allergen specific IgE testing. Pediatr Allergy Immunol. 2008;19:325-331.
  9. Sampson HA, et al. Food allergy: a practice parameter update 2014. J Allergy Clin Immunol. 2014;134:1016-1025.
  10. National Institute of Allergy and Infection Diseases, National Institutes of Health. Report of the NIH Expert Panel on Food Allergy Research. 2006. Www3.niad.nih.gov/topics/foodAllergy/research/ReportFood/Allergy.htm. Accessed December 2017.
  11. PhadiaTM ImmunoCAPTM Specific IgE Directions for Use for the Phadia 250 Laboratory System. Issued September 2017.
  12. Matricardi P.M et al. EAACI Molecular Allergology User’s Guide P. M. et al PAI 2016;27(suppl23): 1-250.
  13. Zethraeus N, et al. Health-care cost reduction resulting from primary-care allergy testing in children in Italy. Ital J Pediatr. 2010;36:61.
  14. Nwaru BI, et al. The epidemiology of food allergy in Europe: a systematic review and meta-analysis. Allergy. 2014;69(1):62-75.
  15. Burks AW, et al. ICON: food allergy. J Allergy Clin Immunol. 2012;129:906-920.
  16. Sicherer SH. Clinical Aspects of Gastrointestinal Food Allergy in Childhood. Pediatrics. 2003;111(6 Pt 3):1609-1616.
  17. Yunginger JW, et al. Quantitative IgE antibody assays in allergic diseases. J Allergy Clin Immunol. 2000;105(6pt1):1077-1084.