Clinical Background
Food allergies are a common form of allergic presentation in childhood.
Epidemiology
- Incidence
- Varies by geographic region
- Increased incidence reported over the past 10 years (especially peanut allergies)
- Age
- Up to 6% of children <3 years of age are affected
- More common in children
- Sex
- Equal gender distribution
Risk Factors
- History of asthma in patient
- History of parent or sibling with atopy or asthma
Pathophysiology
- Any food can potentially sensitize the immune system and cause production of antibody
- Foods that are more likely candidates include those that are
- Water soluble
- Resistant to heat
- Acidic
- Proteolytic
- Most food allergies are IgE mediated
- 90% of IgE-mediated allergies are caused by only eight foods: cows milk, soy, chicken egg, peanuts, tree nuts, fish, crustaceans and wheat
- Non IgE-mediated reactions are common to soy, wheat or cows milk
- Wheat, milk, egg and soy allergies commonly disappear gradually with age
Clinical Presentation
- Classic IgE-mediated (immediate hypersensitivity)
- Reaction occurs within the hour after food ingested
- Symptoms include urticaria, erythema, angioedema, oral pruritus, respiratory symptoms (similar to asthma or allergic rhinitis), anaphylaxis, nausea, diarrhea,
- Mixed IgE, non-IgE
- Occurs 1 to 24 hours after food ingested
- Symptoms include vomiting, diarrhea, colitis, asthma, atopic dermatitis
- Non-IgE (cell-mediated)
- Occurs 24 hours after food ingested
- Symptoms include diarrhea, atopic dermatitis, failure to thrive, severe or persistent infantile colic
Treatment
- Avoidance of foods that patient is sensitive to
- Requires careful reading of packaging, in particular for nut allergies, since many products are produced in factories where nut residue may be present
- Warnings on packages do not correlate with actual risks
- Must have epinephrine kits available for those with documented severe food allergies or children with allergies and coexistent asthma
Prevention
- Avoidance of cow milk and dairy products until 6 months of age
- Avoidance of supplemental feeding and solid foods until 6 months of age
See Also
Diagnosis
Diagnosis
- Indications for testing - medical history (pruritus, urticaria, gastrointestinal symptoms, angioedema anaphylaxis) indicating temporal association between food ingestion and symptoms (<2 hours), chronic diarrhea and failure to thrive in children
- Laboratory Testing
- Skin testing (pin prick) is no longer necessary, although it is generally less costly
- Specific food serum IgE testing along with appropriate history - group or panel allergen tests may be helpful
- Serum tryptase - elevated at 1-4 hours after anaphylaxis and can help confirm diagnosis
- Other tests
- Food challenges may be helpful but should not precede IgE testing
- May be dangerous in certain patients to do food testing
- Needs to be performed under controlled circumstances with very specific endpoints
- Patch testing - being evaluated in non-IgE mediated food allergy (eg, eosinophilic esophagitis)
| Tests |  |
Tests generally appear in the order most useful for common clinical situations
| Test name: Allergens, Food, Common Adult Food
|
| ARUP #: 0050486 |
| Methodology: ImmunoCAP®
|
| Use: Tests for the 11 most common food allergens and total serum IgE (clam, egg white, codfish/whitefish, corn, cow-milk, peanut, shrimp, scallop, soybean, walnut and wheat) |
| Limitations: Does not test for any other allergens |
| Follow-up: Individual allergen testing (see additional ordering notes) |
| Test name: Tryptase
|
| ARUP #: 0099173 |
| Methodology: Fluorescence Immunoassay
|
| Use: Helpful in confirming food allergies as the cause of anaphylaxis |
Additional Information
ARUP Laboratories offers individual food allergen testing. Refer to Food Allergies at www.arupconsult.com for individual food allergen tests in the ARUP Laboratory Test Directory.
References
Guidelines
Fiocchi A, Assa'ad A, Bahna S. Food allergy and the introduction of solid foods to infants: a consensus document. Adverse Reactions to Foods Committee, American College of Allergy, Asthma and Immunology. Ann Allergy Asthma Immunol.
2006;
97(
1):
10-20.
Food allergy: a practice parameter. American Academy of Allergy, Asthma and Immunology - Medical Specialty Society American College of Allergy, Asthma and Immunology - Medical Specialty Society Joint Council of Allergy, Asthma and Immunology - Medical Specialty Society. 2006 Mar. 68 pages. NGC:004958General References
Asero R, Ballmer-Weber BK, Beyer K, Conti A, Dubakiene R, Fernandez-Rivas M, Hoffmann-Sommergruber K, Lidholm J, Mustakov T, Oude Elberink JN, Pumphrey RS, Stahl Skov P, van Ree R, Vlieg-Boerstra BJ, Hiller R, Hourihane JO, Kowalski M, Papadopoulos NG, Wal JM, Mills EN, Vieths S. IgE-mediated food allergy diagnosis: Current status and new perspectives. Mol Nutr Food Res.
2007;
51(
1):
135-147.
Assa'ad AH. Gastrointestinal food allergy and intolerance. Pediatr Ann.
2006;
35(
10):
718-726.
Bischoff SC. Food allergies. Curr Gastroenterol Rep.
2006;
8(
5):
374-382.
Cox H. Food allergy in infants. Practical and clinical considerations (2). Community Pract.
2006;
79(
12):
406-407.
Cox H. Food allergy in infants: Practical and clinical considerations (1). Community Pract.
2006;
79(
11):
370-371.
El-Gamal YM, Hossny EM. Respiratory food allergy. Pediatr Ann.
2006;
35(
10):
733-740.
Fasano MB. Dermatologic food allergy. Pediatr Ann.
2006;
35(
10):
727-731.
Ferreira CT, Seidman E. Food allergy: a practical update from the gastroenterological viewpoint. J Pediatr (Rio J ).
2007;
83(
1):
7-20.
Knight AK, Bahna SL. Diagnosis of food allergy. Pediatr Ann.
2006;
35(
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709-714.
Medical Reviewers
Hill, Harry R., M.D. Group Medical Director, Laboratory of Immunology, ARUP Laboratories, and Executive Director of the ARUP Institute for Clinical and Experimental Pathology; Professor and Division Head, Clinical Pathology, University of Utah
Litwin, Christine, M.D. Medical Director, Immunology at ARUP Laboratories; Professor, Clinical Pathology, University of Utah
Comprehensive Review: September 2008
Last Update: September 2008
