Allergy Testing

Question 1

What are the four different types of allergy tests?

Answer 1

immediate hypersensitivity skin testing, serum IgE antibody testing, nasal smears for eosinohils, delayed hypersensitivity skin tests (patch testing)

Question 2

What are the two most common food allergens for anaphylactic rxns?

Answer 2

peanut and seafood

Question 3

During what season are tree and grass pollens common?

Answer 3

spring

Question 4

During what season are weed pollens common?

Answer 4

late summer/fall

Question 5

What does a personal or family history of atopic disease put someone at risk for?

Answer 5

allergies

Question 6

What diseases are included in the atopic triad?

Answer 6

allergic rhinitis, eczema, asthma

Question 7

What is atopy?

Answer 7

tendency to be “hyperallergic”

Question 8

What are indications for allergy testing in someone who has rhinitis?

Answer 8

Symptoms not controlled by medications and allergen avoidance

Question 9

What are indications for allergy testing in someone who has asthma?

Answer 9

Persistent asthma in patients exposed to perennial indoor allergens

Question 10

What are indications for allergy testing in someone who has a suspected food allergy?

Answer 10

Previous suspected systemic reaction to food

Question 11

What are indications for allergy testing in someone who has a suspected drug allergy?

Answer 11

Previous suspected systemic reaction to drug, and clinical indication for suspected drug

Question 12

What are indications for allergy testing in someone who has a suspected insect sting?

Answer 12

Previous suspected systemic reaction to insect sting

Question 13

What disease conditions is an immediate hypersensitivity test used to diagnose?

Answer 13

allergic rhinitis, allergic asthma, food allergy, penicillin allergy and stinging insect hypersensitivity

Question 14

Who is at high risk for anaphylaxis during an immediate hypersensitivity skin test?

Answer 14

Poorly controlled asthma and reduced lung function. History of severe reactions to small amounts of allergen. Significant cardiovascular disease and elderly patients

Question 15

What kind of allergy testing should be done if patients can’t have a hypersensitvity skin test?

Answer 15

immunoassay allergy testing

Question 16

Why are beta blockers and ACE inhibitors contraindicated for skin tests?

Answer 16

they mask symptoms of anaphylaxis

Question 17

Why might a skin test yield false negative results?

Answer 17

mast cell refractory period

Question 18

Why should patients who have skin conditions (dermographism, urticaria, and cutaneous mastocytosis) not be skin tested?

Answer 18

false positive results are common

Question 19

What is dermatographism?

Answer 19

caused by mast cells in the surface of the skin releasing histamines without the presence of antigens, due to the presence of a weak membrane surrounding the mast cells.

Question 20

What is mastocytosis?

Answer 20

group of rare disorders of both children and adults caused by the presence of too many mast cells

Question 21

Why are skin tests typically not done for patients who are currently taking TCAs, muscle relaxants, or antimemtic druge?

Answer 21

these drugs would need to be stopped for up to 2 weeks. do serum testing instead

Question 22

How would tacrolimus (Protopic) used to treat eczema, affect a skin test?

Answer 22

decrease skin reactivity, give false negative

Question 23

What are benefits of skin testing?

Answer 23

Most rapid, sensitive, and cost effective testing modality for the detection of IgE-mediated disease

Question 24

How is a positive skin test determined?

Answer 24

Wheal equal or larger in size to that associated with histamine control. Wheal diameter larger than 3mm (histamine control usually produces wheal about 3mm diameter

Question 25

How do intradermal injections compare to percutaneous injections?

Answer 25

higher sensitivity but lower specificity

Question 26

For what suspected allergens do you reserve intradermal injections?

Answer 26

venom and PCN when percutaneous tests are negative

Question 27

What is there a greater risk of with intradermal injections?

Answer 27

systemic rxn

Question 28

What are the general principles for the interpretation of a positive skin test?

Answer 28

result ONLY indicates presence of IgE specific to that allergen. You can be sensitized to something but that doesn’t mean it is an allergy

Question 29

What is the only medication that skin testing has been standardized for?

Answer 29

PCN (penicillin)

Question 30

How does the specific IgE (RAST) test compare to skin testing?

Answer 30

less sensitive, more expensive

Question 31

When is the RAST preferable to skin testing?

Answer 31

High risk for anaphylactic reaction to skin testing.

Presence of interfering medications

Question 32

What is the specific IgE (RAST) test?

Answer 32

a blood test that measures the levels of allergy antibody or IgE, produced when your blood is mixed with a series of allergens in the lab

Question 33

What do nasal smears usually show in cases of allergic rhinitis?

Answer 33

predominance of eosinophils

Question 34

What is a Wright stain used for?

Answer 34

to differentiate blood cells

Question 35

What can a Hansel stain be used for?

Answer 35

to see if there is a predominance of eosinophils (stain red) or neutrophils (stain blue)

Question 36

When is the most appropriate time to consider specific allergy testing?

Answer 36

if a patient would likely benefit from immunotherapy

Question 37

What does any positive test for an allergy need to be confirmed with?

Answer 37

history of reactivity and in some cases allergen challenge to confirm