II. Indications
- Refractory Allergic Rhinitis
- Refractory Asthma
- Food Allergy or drug allergy suspected
- Insect sting allergy suspected
- Angioedema
- Contact Dermatitis
III. Types: In Vivo Tests
-
Hypersensitivity Skin Testing (Skin Prick Test or Intradermal Test)
- IgE immediate Type 1 Hypersensitivity Reaction
-
Patch Testing
- Contact Dermatitis (Delayed Type 4 Hypersensitivity, T Cell-mediated response)
- Oral Food Challenge
- IgE immediate Type 1 Hypersensitivity Reaction
- Indicated in Food Allergy
IV. Types: In Vitro Tests
-
Allergen Specific IgE Antibody Measurement (via ImmunoCAP or RadioAllergoSorbent Test)
- IgE immediate type Hypersensitivity
- Indicated in patients at risk for severe Anaphylaxis with allergan exposure
- Not impacted by Dermatographism or dermatitis (and not altered by Antihistamine use)
V. Devices
- Morrow-Brown Needle
- Multi-Test (Lincoln Diagnostics)
- Quintest (Bayer)
- Modified RadioAllergoSorbent Test (RAST)
- Quidel finger stick device
VI. Approach
- Inhalant Allergy
- See Regional Allergy Screening
- Skin Testing is preferred (most cost-effective)
- IgE specific Antibody testing panels are available for each U.S. region
-
Food Allergy
- Food Allergy testing has a high False Positive Rate and should only be performed based on a specific history
- Start with a history of common Food Allergy causes
- Hen's eggs, cow's milk or peanuts (85% of food allergies in children and teens)
- Fish or shellfish
- Soy
- Tree nuts (e.g. cashews, walnuts)
- Wheat allergy (gluten sensitivity, Celiac Sprue)
- Patient should eliminate food they suspect as allergan
- If symptoms improve after food elimination, then consider Allergy Testing for that food item
-
Skin Testing or IgE specific Antibody testing
- High Negative Predictive Value
- Positive test results are of limited value (high False Positive Rate)
- Many patients may tolerate food items despite a positive test
- Avoid broad-based Food Allergy panel screening
- Food challenge
- Confirms negative Allergy Testing
-
Insect Allergy
- Testing indicated in suspected Stinging InsectAnaphylaxis or diffuse skin reactions
- Test via Skin Testing or IgE specific Antibody testing
- Test for most common Insect allergans (e.g. fire ants, honey bees, yellow hornets, yellow jackets, wasps)
- Immunotherapy for those at high risk for severe future reactions
- Obtain Serum Tryptase level
- Evaluate for Mast Cell activation syndrome if Serum Tryptase >11.5 ng/ml
-
Antibiotic allergy (esp. Penicillin Allergy)
- Only 1-10% of self-reported Penicillin Allergy have an abnormal skin test
- Penicillin Skin Testing has a Negative Predictive Value >95%
- Often confirmed with a monitored oral challenge in allergy clinic
- Penicillins may safely be prescribed after negative skin test
VII. References
- (1999) NPI Allergy Testing Conference, Las Vegas
- Bright (2023) Am Fam Physician 108(2): 159-65 [PubMed]
- Chang (2018) Am Fam Physician 98(1): 34-9 [PubMed]
- James (2002) Am Fam Physician 66(4):621-6 [PubMed]