Rhinology Allergy Diagnostic Testing

Question 1

Although it is no longer regularly used in the
United States, what test can be used to look for
eosinophils versus neutrophils in the nasal mucus
in an effort to distinguish eosinophilic rhinitis from
other rhinitis?

Answer 1

Nasal cytology

Question 2

Allergy testing to specific allergens can be done

via which two broad techniques?

Answer 2

● In vivo (skin testing)

● In vitro (serum testing)

Question 3

What immunoglobulin is being tested for with in

vivo skin testing?

Answer 3

Antigen-specific IgE

Question 4

What are the two most common locations for

performing skin testing?

Answer 4

● Volar surface of the forearm

● Back

Question 5

What type of in vivo allergy test is performed
using scratch, prick/puncture, or patch to
challenge a patient by introducing allergen into
the epidermis only?

Answer 5

Epicutaneous testing

Question 6

What type of in vivo allergy test is performed
using intradermal techniques to place antigen into
the superficial dermis?

Answer 6

Percutaneous testing

Question 7

What variables impact both epicutaneous and

percutaneous skin testing?

Answer 7

● Age of the skin (very young and very old may be less
sensitive)
● Area of the body being tested (sensitivity: upper back >
lower back > upper arm > lower arm)
● Skin pigmentation (darker skin colors may be less sensitive)
● Concurrent medications
● Potency and biologic stability of the allergen test extract

● Dermatopathology: Dermatographism, eczema → con-
traindications, including degree of sensitization, recent

anaphylaxis, recent exposure, prior immunotherapy

Question 8

During skin testing, what controls are commonly

used?

Answer 8

● Negative control: Glycerin-saline, saline, allergen diluent
● Positive control: Histamine (10 mg/mL)

Question 9

During skin testing, what term is used to describe
the white (blanched) raised area at the site of the
allergen application?
The area of erythema that extends beyond this
raised region?

Answer 9

Wheal

Flare

Question 10

Why is scratch testing (small superficial
lacerations made in the skin, a drop of
concentrated antigen then applied) not recommended for skin testing?

Answer 10

Poor reproducibility, variable sensitivity, poor specificity,
frequent false-positives, painful, and reaction may be due to
trauma to skin instead of reaction to allergen

Question 11

During an in vivo epicutaneous allergy test, a drop
of antigen is placed on the patient’s skin. The
tester then uses a needle, lancet, or prick device
(single or multiple tines) to puncture or prick the
skin through the drop of antigen and deliver the
antigen to the epidermis. What is this called?

Answer 11

Skin-prick or puncture testing. It is the most commonly

used test.

Question 12

What instrument(s) can be used to perform a
skin prick or puncture test?

Answer 12

Hypodermic needle, solid-bore needle, lancet ± bifurcated
tip, multiple-head devices (more commonly used because
of OSHA concerns regarding inadvertent health care worker
needle sticks)
Pass through the droplet, then the skin at a 45- to 60-
degree angle to the skin, lift and break the skin without
causing bleeding for the prick test; or the skin device can be
passed through the drop at a 90-degree angle to the skin
for puncture test.

Question 13

After performing a skin prick or puncture, how
long should you wait before assessing the
response?

Answer 13

15 to 20 minutes

Question 14

How can you assess the allergic response to a skin

test (epicutaneous or percutaneous)?

Answer 14

Direct measurement: Recommended scoring system
● Longest diameter or longest diameter and orthogonal
diameter (perpendicular) of wheal in millimeters
● Presence or absence of flare and size in millimeters as in
preceding
● Presence or absence of pseudopods
Classically based on a 0 to 4 + system: Based on wheal and
flare compared with the negative control and the presence
or absence of pseudopods
Subjective analysis is no longer recommended by the
American Academy of Allergy, Asthma and Immunology

because of interphysician variability in scoring and inter-
pretation.

Question 15

The American Academy of Allergy, Asthma, and
Immunology guidelines for skin testing
recommend that wheals < 3 mm should not be
considered positive. Why?

Answer 15

Trauma can affect wheal size.

Question 16

What are the major disadvantages to skin-prick

tests?

Answer 16

Semiqualitative (less objective than intradermal testing).
Low degrees of sensitivity may be missed → false-negative
results.

Question 17

When should you use an intradermal/

percutaneous allergy test?

Answer 17

When the primary goal of testing is increased sensitivity, or
for evaluating drug or venom anaphylactic reactions

Question 18

Describe the technique used for single dilutional

intradermal (percutaneous) allergy testing.

Answer 18

1. Using a small needle (generally 26- or 27-gauge needle
   at 45-degree angle), inject 0.02 to 0.05 mL of antigen
   diluted to 1:500 to 1:1000 weight/volume intradermally
   (create a 2- to 3-mm bleb in dermis).
2. Positive control: Histamine (0.001 mg/mL) if needed;
   can be excluded if reaction was proven by prick testing.
   Negative control also performed.
3. Wait 10 to 15 minutes, and then assess response.

Question 19

What is the major risk in using intradermal allergy

testing, and how can this risk be decreased?

Answer 19

Significant systemic reaction (anaphylaxis). Patients should
be screened with prick/puncture testing initially. They can

also be screened with very dilute concentrations adminis-
tered intradermally.

Question 20

What part of the body is commonly used for

intradermal testing and why?

Answer 20

Volar surface of the forearm. To allow a tourniquet to be

placed in case of systemic symptoms

Question 21

True or False. Single-dilution intradermal skin

testing is more specific than it is sensitive.

Answer 21

False. High sensitivity, less specificity. It has a higher false-
positive rate than skin prick testing.

Question 22

What type of allergy test requires the sequential
administration of fivefold-diluted antigens
intradermally, beginning with dilute concentrations?

Answer 22

Intradermal dilutional testing, also called skin endpoint

titration

Question 23

What does the American Academy of Allergy,
Asthma and Immunology recommend as a starting
dose of intracutaneous extract solution in patients
with a preceding negative prick test?

Answer 23

100- to 1000-fold dilutions of the concentrated extracts

used for prick/puncture tests.

Question 24

What size needle/syringe is recommended during

intradermal dilutional testing?

Answer 24

0.5- or 1.0-mL syringe with a 26- to 30-gauge needle (can

come as a single unit)

Question 25

What volume of antigen concentrate should be | injected during intradermal dilutional testing?

Answer 25

0.01 mL (Goal is to create a 4-mm round wheal.)

Question 26

After injection of 0.01 mL and creation of a 4-mm wheal, you appropriately wait 10 minutes to measure the final wheal. If the injected solution was inert diluent, what diameter do you expect based on passive physical diffusion in the skin?

Answer 26

5 mm

Question 27

What is required for a whealing response to be considered positive during intradermal dilutional testing?

Answer 27

A final wheal size of 7 mm, which is 2 mm larger than the expected size at 10 minutes from physical diffusion alone. Flare is not measured during this type of testing. This topic is somewhat controversial, as many practitioners use 3 mm.

Question 28

During intradermal dilutional testing, you note that the no. 6 dilution produces a 5-mm wheal after 10 minutes. You then inject the no. 5 dilution and again note a 5-mm wheal after 10 minutes. You therefore inject the no. 4 dilution and note a 7-mm wheal. What should you do?

Answer 28

The no. 4 dilution demonstrated progressive whealing, so you must perform a confirmatory wheal by injecting the no. 3 dilution. If this is > 7 mm, it would suggest progressive whealing, and the no. 4 dilution would be considered the end point of the examination. A confirmatory wheal must grow by at least 2 mm.

Question 29

Describe the technique used for intradermal | dilutional testing.

Answer 29

● Dilutions created and labeled as no. 1 to no. 6, with no. 6 representing the weakest concentration and the least likely to induce a response ● Inject a negative control: 4 mm wheal → 5 mm or less. ● Inject a positive control (histamine: 0.0004 mg/mL): 4- mm wheal → 7 mm or more ● 0.01 mL of the no. 6 dilution is injection intradermally to create a 4-mm wheal ● Wait 10 minutes. ● If the wheal is 5 mm, it is considered negative. If it is 7 mm or larger, it is considered positive. Continue with dilution no. 5. ● If at any dilution you note growth of the wheal > 2 mm over the negative wheal (so 7 mm or more), continue with the next dilution. ● It the next dilution demonstrates progressive growth (an additional 2 mm), stop the test. The first wheal to demonstrate growth is the endpoint dilution, and the second dilution to demonstrate progressive whealing is the confirmatory wheal.

Question 30

After a positive fivefold sequential intradermal dilutional testing, what dilution should be used as a safe starting point for immunotherapy?

Answer 30

The endpoint dilution (the wheal that initiated progressive | whealing)

Question 31

What test uses skin-prick/puncture testing to determine the approximate degree of allergic sensitization, followed by specific sequential intra- dermal dilutional tests to assess further the prick/ puncture results and to determine an endpoint dilution that can be used for initiating immunotherapy?

Answer 31

Modified quantitative testing (MQT) MQT is Frequently used by otolaryngologists practicing in the allergy field. It is used for its reproducibility, decreased cost, high sensitivity and specificity, and excellent correla- tion with full intradermal dilutional testing batteries.

Question 32

Describe the technique used when performing a | modified quantitative test for allergic disease?

Answer 32

● Use mutlitest (a device with multiple skin prick/puncture device). ● Wait 20 minutes. ● Wheal < 3 mm → Place no. 2 dilution in upper arm. → Wait 10 minutes → assess wheal ○ ≤ 6 mm = Negative ○ ≥ 7 mm = Endpoint: no. 3 dilution ○ Wheal 3 to 8 mm → place no. 5 dilution in upper arm. ● → Wait 10 minutes → assess wheal: ○ ≤ 5 mm = Endpoint: no. 4 dilution ○ 7 to 8 mm = Endpoint: no. 5 dilution ○ ≥ 8 mm = Endpoint: no. 6 dilution ○ Wheal ≥ 9 mm = Endpoint: no. 6 dilution

Question 33

What medications can suppress the wheal and | flare response for 48 to 72 hours?

Answer 33

First-generation antihistamines (i.e., brompheniramine, chlor- pheniramine, clemastine, diphenhydramine, hydroxyzine)

Question 34

Which medications should be avoided for 7 days because of suppression of the wheal and flair response?

Answer 34

Second-generation antihistamines and tricyclic antidepres- | sants

Question 35

What are the second-generation antihistamines that should be avoided at least 7 days before skin testing?

Answer 35

Cetirizine, loratidine, fexofenadine, levocetirizine. | Note: Desloratidine should be avoided for > 14 days.

Question 36

True or False. Leukotriene receptor antagonists should always be stopped at least 7 days before to skin testing.

Answer 36

False. They have not been shown to routinely inhibit wheal and flare response. They can be stopped in individual patients in whom the wheal and flare response is thought to be impacted by the medication.

Question 37

What impact do intranasal or systemic corticosteroids have on the wheal and flare response during skin testing?

Answer 37

Little to none

Question 38

To resuscitate a patient adequately in the unlikely event he or she develops anaphylaxis after skin testing in your office, what medication(s) should be stopped?

Answer 38

β-blockers (both topical and systemic)

Question 39

What test measures serum concentrations of | allergen-specific IgE antibodies?

Answer 39

RAST and modified RAST (has better sensitivity and more consistent scoring but is based on the original RAST immunoassay)

Question 40

Describe the steps involved in the original RAST | immunoassay?

Answer 40

● Allergen-bound paper disk is placed in test tube. ● Patient’s serum is added and antigen-specific IgE binds the antigen. ● Excess serum and IgE are washed away. ● Radiolabeled anti-IgE antibodies are added to the test tube and bind the antigen-specific IgE already bound to antigen on the paper disk. ● Excess is washed away. ● Gamma counter is used to determine the amount of bound IgE.

Question 41

What are the benefits of immunoassay testing for | allergic disease over skin testing?

Answer 41

Condition of skin does not matter, the results are not affected by drugs, no risk of anaphylaxis, greater patient convenience, quality control is easier, allows for quantitative assessment in preparation for immunotherapy, greater specificity. It may be less sensitive and is more expensive.

Question 42

What are the benefits of skin testing over | immunoassay for allergic disease?

Answer 42

Less time and expense to perform, increased sensitivity, | wider variety of antigens to test, faster results

Question 43

What level of total IgE in a patient’s serum is | suggestive of allergy?

Answer 43

> 200 IU. However, lower concentrations do not rule out | allergy.

Question 44

When should in vitro studies be recommended?

Answer 44

Patient is uncomfortable undergoing skin testing. Patient is not responding to medical therapy or doing poorly on immunotherapy. Patient is unable or unwilling to stop taking antihistamines, tricyclic antidepressants, or β-blockers. Patient has eczema or dermatographism. Patient has venom sensitivity Patient has possible IgE-mediated food sensitivity.

Question 45

During a nasal provocation test, a patient is exposed to an allergen to determine whether exposure to a clinically significant allergen results in symptoms. The outcome can be measured based on symptoms and what other diagnostic tool?

Answer 45

Rhinomanometry