ENT - Allergy

Question 1

What is the incidence of allergy in the UK?

Answer 1

Asthma 9.4%
Allergic Rhinitis 5.4%
Eczema 1%
Food Allergies 1-2%
Multiple allergies 3.7%

Rapid increase began in the 1960s
Increased in developed countries

Question 2

What is the immunoglobulin driving allergic reactions?

Answer 2

IgE

Question 3

What is allergy?

Answer 3

Hypersensitive disorder of the immune system.

Allergic reactions occur to normally harmless environmental substances known as allergens; these reactions are aquired.

The allergic reaction is an exaggerated or inappropriate immune reaction and causes damage to the host.

Question 4

Name some common allergic reactions

Answer 4

Eczema
Allergic rhinitis
Asthma
Food allergies

Question 5

What is an allergen?

Answer 5

Antigen that causes allergic reactions

Usually proteins

Question 6

How do allergic reactions vary?

Answer 6

Depending on the individual, allergen and mode of introduction.

Symptoms can be systemic or localised
e.g. asthma localised to respiratory system and eczema to dermis

Question 7

What are some of the broad symptoms and signs of allergy?

Answer 7

Sneezing
Nasal Congestion
Runny nose

Swelling and tenderness of the mouth
Difficulty breathing

Flushing or rash
Burning and itching of skin
Hives

Nausea/vomiting
Abdominal cramps
Diarrhoea

Question 8

What is the pathophysiology of allergic reaction?

Answer 8

IgE mediated triggering of mast cells and subsequent accumulation of inflammatory cells at sites of antigen deposition

Question 9

What is the pathophysiology of developing allergy?

Answer 9

Fist allergen exposure:
-Response with T cells and B cell producing IgE

IgE circulates in the blood and binds to an IgE-specific receptor (mast cells and basophils)

Question 10

What is the acute allergic response?

Answer 10

Exposure of allergen
Allergen specific IgE

Degranulation with release of histamine, cytokines, interleukins, leukotrienes, and prostaglandins from their granules causing systemic effects, such as vasodilation, mucous secretion, nerve stimulation and smooth muscle contraction

Question 11

What is the late phase response in allergy?

Answer 11

2-4 hours

this is due to migration of other leukocytes, such as neutrophils, lymphocytes, eosinophils and macrophages to the initial site

Question 12

What are the risk factors for allergy?

Answer 12

Host factors are HEREDITY, race and age

Environmental factors are alterations in exposure to infections diseases during early childhood, environmental pollution, allergen levels and dietary changes.

Question 13

How is allergy diagnosed?

Answer 13

Skin test:
-responses to known allergens
(up to 15% false positives, +ve and -ve control used to minimise this)

RAST:
-Presence and levels of allergen specific IgE

Question 14

What is the treatment for allergy?

Answer 14

Multiple modalities

Allergen avoidance
Pharmacotherapy
Immunotherapy

Question 15

What is immunotherapy?

Answer 15

Give tiny, tiny amounts of allergen and slowly build up the dose.

Desensitising the immune system to allergen

Must be done under controlled conditions incase anaphylaxis

Very hard and a lot of work but only treatment to actually treat disease rather than symptomatic relief.

Useful for allergic rhinitis, allergic asthma, allergic conjunctivitis etc
Not for food allergy, urticaria, atopic dermatitis

Question 16

What is the pharmacotherapy for allergy?

Answer 16

Several drugs: to prevent activation of cells and degranulation processes or to block the action of allergic mediators.

Antihistamines
Glucocorticoids
Epinephrine
Theophylline
Cromolyn sodium
Antileukotrienes

Question 17

What is allergic rhinitis?

Answer 17

Allergic inflammation of the nasal airways

Occurs when allergen is inhaled by an individual with a sensitised immune system

Question 18

What are the symptoms of allergic rhinitis?

Answer 18

Sneezing
Coughing
Wheezing
Runny nose
Weepy eyes
Itchyness

Question 19

What are the two classifications of allergic rhinitis?

Answer 19

Seasonal

Perennial