1. Allergy Testing Melisa Steele, CPNP
Intermountain Healthcare Memorial Clinic
Allergy and Asthma Department
September 21, 2012

2. Objectives
Discuss who needs to be allergy tested and when to perform testing
Summarize allergy testing guidelines
Identify acceptable methods of allergy testing

3. Testing done in an Allergy Office
Food Allergy Tests
Milk, Egg, Wheat, Soy
Fish, Shellfish, Peanuts, Tree nuts
Fresh Fruits and Vegetables
Other foods as needed
Seasonal and Perennial Allergy Tests
Pollen, Dust Mites, Mold and Animals
Oral Food Challenges
Bee Venom Allergy Tests
Antibiotic Allergy Tests
Refer to Dermatology
Contact dermatitis allergies-adhesives, plastics, etc.

4. At what age can you expect allergies?
Food allergy
Any age, typically start testing patients after 6 months of age
Perennial Allergies (animals, dust mites, mold)
Starts as young as 6 months
Seasonal Allergies
Earliest-age 2
Not common before age 4

5. Types of adverse reactions to food
Source: Journal of Allergy and Clinical Immunology 2010; 126:S1-S58 (DOI: /j.jaci )
1.Adverse reactions to food have been reported in up to 25% of the population at some point in their lives with the highest prevalence observed during infancy and early childhood.
2. True prevalence of food allergy is much lower than the number of suspected food allergies % of suspected food allergies are not food allergies
3. Lots of cross-over of symptoms with IgE mediated and non-IgE mediated reactions, especially GI
4. EoE: localized eosinophilic inflammation of the esophagus. Both IgE and non-IgE mechanisms involved. 95% show marked improvement when on a food elimination diet.
5. Eosinophilic gastroenteritis-both IgE and non-IgE

6. How is IgE related to allergic reactions?
IgE mediated reaction:
Your body misinterprets an antigen (food, pollen, animal, venom) it is exposed to and makes IgE (antibody) to protect itself.
IgE then attaches to floating mast cells/basophils.
The next time the antigen appears, it binds to the IgE
This triggers the attached mast cell to release chemicals that cause allergic symptoms (skin, respiratory, GI, anaphylaxis.)
Most of the testing done in an allergy office relates to measuring IgE, will refer to GI or dermatology for non IgE diagnoses
Measuring IgE indicates sensitization not clinical reactivity

7. Common IgE-mediated Food Allergy Symptoms
Cutaneous
Gastrointestinal
Acute urticaria and angioedema
Angioedema of the lips, tongue or palate
Erythema
Oral pruritus
Pruritus
Tongue swelling
Atopic dermatitis
Nausea
Respiratory
Abdominal pain
Nasal congestion
Vomiting
Laryngeal edema
Diarrhea
Cough
Miscellaneous
Dyspnea
Uterine contractions
wheezing
Sense of “impending doom”
Cardiovascular
Tachycardia
Hypotension
Dizziness
Fainting

8. What do you need to know about food allergies?
95% of food allergies are caused by the 8 main food allergens
milk, egg, wheat, soy, peanut, tree nut, fish and shellfish.
Food allergy is more common in children than adults
6-8% of children under age 5.
Most food allergies appear within the first 2 years of life although peanut, tree nut and seafood allergies may begin at any age.
Milk, egg, wheat and soy allergies usually resolve in childhood.
Peanut, tree nut, fish/shellfish are more likely to persist.
Food allergy that starts in adult life tends to persist.
Allergy to sesame seed is becoming more common.

9. Need to know continued:
About half of individuals with a food allergy will react to more than one food.
No diagnostic testing is available to predict severity of future reactions.
Risk factors for the development of food allergy:
Family history of atopy
Presence of atopic dermatitis, especially moderate to severe AD, in children under the age of 5
Adults: Shellfish-2.5%, Fish-0.5%, Peanut 0.6%, tree nut- 0.5%

10. When should food allergy be suspected or who needs to be tested?
In individuals presenting with anaphylaxis or with typical symptoms (e.g. urticaria, edema, wheezing, mouth itch, cough, nausea/vomiting, etc.)
occurs within minutes to hours of ingesting food,
especially in young children
if symptoms have followed the ingestion of a specific food on more than 1 occasion
Children and adults diagnosed with certain disorders
Eosinophilic esophagitis, enterocolitis, enteropathy, and allergic proctocolitis
Children less than 5 years old with persistent atopic dermatitis in spite of optimized management and topical therapy
30-40% will have food allergy

11. Things to Know Before Sending a Patient for Allergy Testing
All antihistamines must be stopped 7 days prior to testing.
Tricyclic antidepressants should be stopped 10 days before testing but only under the direct supervision of the prescribing physician and should not be abruptly terminated.
H2 blockers may suppress test results and might need to be stopped as well. Don’t stop unless instructed at first visit.
Patient should bring any pertinent studies or results with them (chest or sinus CT scans, xrays, copies of previous allergy testing, list of current medications, etc).
The first visit can last 2-2 ½ hours.

12. Food Allergy Evaluation
Detailed history:
List of suspected foods
Quantity of food eliciting a reaction
Reproducibility of reaction
Time between exposure and reactions
Clinical manifestations
Resolution of symptoms with elimination of the suspect food
Treatment given and overall duration of symptoms after each exposure
Physical Exam
Focus on suspected target organ systems (cutaneous, respiratory, gastrointestinal)

13. Food Allergy Evaluation
Skin prick test/Skin puncture test (SPT)
Safe and useful for identifying foods potentially provoking IgE-mediated food-induced allergic reactions
SPT alone cannot be considered diagnostic of food allergy
Testing is done on the lower arm or back
Always place a positive histamine control and a negative saline control
Wheals and flares are measured in millimeters

14. Food Allergy Evaluation
Skin prick test/Skin puncture test (SPT)
Positive SPT is considered a wheal 3mm greater than the negative control
Positive SPT only indicates presence of IgE antibody, NOT clinical reactivity (~50% false positive) therefore NOT a good screening tool
Negative SPT essentially excludes IgE antibody (>95%)
Results are “immediate”, typically within 15 minutes following the SPT
Intradermal tests should not be used

15. Food Testing Worksheet

16. Allergy panel and lancets

17. Positive egg allergy

18. Food Allergy Evaluation
Allergen-specific serum IgE
Still often referred to as RAST testing which is a specific lab test but RAST testing is outdated. The test is now CAP FEIA even when a RAST panel is ordered.
Not diagnostic when used alone to determine food allergy.
May be more accurate than SPTs to predict clinical reactions; the higher the level, the more likely a reaction will occur.
Does not always correlate with SPT
sIgE measures IgE in the serum
SPTs measure IgE bound to cutaneous mast cells

19. Allergen-specific serum IgE levels (Guidelines only)
Egg
Milk
Peanut
Fish
Soy
Wheat
Reactive if > (no challenge needed, >95% likely to react) 7 15 14 20 65 80
Possible reactive (physician challenge) ↓
Unlikely reactive (home challenge)
<.35
*Under age 2:
Egg: 95% reaction risk for level of 2 kIU/L or more
Milk: 95% reaction risk for level of 5 kIU/L or more

20. Food Allergy Evaluation
Elimination Diets
Especially useful for food allergies related to EoE
Eliminate a single food for 1-6 weeks or go to an elemental diet and slowly add food back in
Oral food challenges
Reasons to challenge
Confirm the diagnosis of food allergy
Determine whether a food allergy has been outgrown
Double blind placebo controlled food challenge- gold standard but not usually done for diagnosis due to time and cost constraints
Open or single-blinded oral food challenges acceptable- often done to see if patient is no longer food allergic (skin & blood tests are negative or significantly decreased)
Baked food challenge first

21. Food Allergy Diagnosis
Diagnosis is based on the results of SPT, serum IgE testing, clinical history, and oral food challange. No single test or history alone can determine an IgE-mediated food allergy.
Oral Allergy Syndrome: Form of localized IgE-mediated contact allergy, usually to raw fruits or vegetables, with symptoms confined to lips, mouth, and throat. Most commonly affects patients who are allergic to pollens. Reactions are usually mild, anaphylaxis is rare.
Birch: apple, apricot, carrot, cherry, kiwi, plum
Ragweed: banana, cucumber, melon, watermelon
Grass: cherry, peach, potato, tomato

22. Seasonal and Perennial Allergy Testing
Trees, grass, weeds
Perennial
Dust mites, mold, animals
Causes an IgE-mediated reaction but anaphylaxis is not common
Reasons for testing
Patient wants to know
Help with pollen/animal avoidance
Immunotherapy
Help control co-morbid conditions (asthma, atopic dermatitis)
Improve quality of life

23. Pollen/Inhalants Testing Worksheet

24. Bee Venom & Antiobiotic Testing
Bee venom testing
Testing is not done if only reaction is a large local
Types of vespids tested
Honey bee
Yellow Jacket
White-faced hornet
Yellow hornet
Wasp
Antibiotic testing
Pen VK is the only antibiotic with standardized testing but all antibiotics can be evaluated
Testing done only for IgE-mediated reactions, not serum sickness or other types of reactions

25. Nonstandard and unproven procedures
Totoal IgG or Allergen-specific IgG4
Applied kinesiology
Provocation neutralization
Hair analysis
Electrodermal testing
Basophil histamine release/activation
Lymphocyte stimulation
Facial thermography
Gastric juice analysis
Endoscopic allergen provocation
Cytotoxicity assays
Mediator release assay (LEAP diet)

26. Resources
Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of the NIAID-Sponsored Expert Panel, The Journal of Allergy and Clinical Immunology, Volume 12, Number 6, December 2010.
Food Allergy and Anaphylaxis Network,
Utah Food Allergy Network,
American Academy of Allergy Asthma & Immunology,
American College of Allergy Asthma & Immunology,