Allergy

Question 1

Allergy

Answer 1

Hypersensitivity of immune system to allergens

Question 2

Allergen

Answer 2

Protein that immune system recognises as foreign and potentially harmful
Leading to allergic immune response
Types of antigen

Question 3

Antigens

Answer 3

Proteins that can be recognised by immune system

Question 4

Atopy conditions

Answer 4

Eczema
Asthma
Hay fever
Allergic rhinitis
Food allergies

Question 5

What are the two main contributors to a child developing an allergy to a food?

Answer 5

Break in skin (eczema or skin infection), allows allergens from environment to cross skin and react with immune system
Child doesn’t have contact with that allergen from GI tract, absence of GI exposure to allergen

Question 6

Hypersensitivity conditions

Answer 6

Asthma
Atopic eczema
Allergic rhinitis
Hay fever
Food allergies
Animal allergies

Question 7

Coombs and Gell classification hypersensitivity

Answer 7

TY1: IgE
TY2: IgG and IgM
TY3: immune complex
TY4: T lymphocytes

Question 8

TY1 hypersensitivity

Answer 8

IgE antibodies to a specific allergen
Trigger mast cells and basophils to release histamine and other cytokines
Immediate reaction
Food allergy

Question 9

TY2 hypersensitivity

Answer 9

IgG and IgM antibodies
React to allergen and activate complement system
Direct damage to the local cells
Examples: HDN, transfusion reactions

Question 10

TY3 hypersensitivity

Answer 10

Immune complexes accumulate and causes damage to local tissues
SLE, rheumatoid arthritis, Henoch-Schonlein purpura

Question 11

TY4 hypersensitivity

Answer 11

Cell mediate hypersensitivity
T lymphocytes
T cells inappropriately activated
Causing inflammation and damage to local tissues
Organ transplant rejection and contact dermatitis

Question 12

History of allergy

Answer 12

Timing after exposure to allergen
Previous and subsequent exposure and reaction to allergen
Symptoms of rash, swelling, breathing, difficulty, wheeze and cough
Previous personal and FH of atopic conditions and allergies

Question 13

Investigations in allergy

Answer 13

Skin prick testing: sensitisation
RAST testing: sensitisation
Food challenge testing: gold standard for diagnosing allergy

Question 14

Skin prick testing

Answer 14

Fresh needle, water control, histamine control

After 15 minutes, size of wheals to each allergen are assessed and compared to the controls

Question 15

Patch testing

Answer 15

Used to diagnose allergic contact dermatitis
Not helpful for food allergies
After 2-3 days assess skin reaction to patch

Question 16

RAST testing

Answer 16

Measures total and allergen specific IgE quantities in patients blood sample

Question 17

Allergy management

Answer 17

Establish and avoid correct allergen
Avoid foods that trigger reactions
Regular hoovering and changing sheets and pillows if there is a dust mite allergy
Staying indoor where pollen count is high
Prophylactic antihistamines where contact is inevitable
Adrenalin auto-injector for patients at risk of anaphylaxis

Immunotherapy

Question 18

Treatment following exposure of allergen

Answer 18

Antihistamines (cetirizine)
Steroids
IM adrenaline

Question 19

Anaphylaxis presentation

Answer 19

History of exposure
Urticaria
Itching
Angio-oedema
Abdominal pain 

SoB
Wheeze
Swelling of larynx, causing stridor
Tachycardia
Lightheadedness
Collapse

Question 20

Anaphylaxis principles of management

Answer 20

Airway: secure airway
Breathing: provide oxygen if required, salbutamol can help with wheezing
Circulation: IV fluid bolus
Disability: lie patient flat to improve cerebral perfusion
Exposure: look from flushing, urticaria, angio-oedema

Question 21

Medications to treat anaphylaxis

Answer 21

IM adrenaline
Antihistamines: oral chlorphenamine or cetirizine
Steroids, hydrocortisone

Question 22

After anaphylaxis

Answer 22

Biphasic reaction
Measure serum mast cell tryptase within 6 hours
Train parents in BLS
Adrenalin auto-injector

Question 23

Adrenalin auto-injector indications

Answer 23

Anaphylaxis reactions
Asthma requiring inhaled steroids
Poor access to medical treatment
Adolescents
Nut/insect sting allergies
Significant co-morbidities

Question 24

How to use adrenalin auto-injection

Epipen

Answer 24

Remove blue cap
Grip device needle end is orange 
Administer injection, hold for 3s
Remove device and massage for 10s
Phone ambulance
Second dose after 5 mins

Question 25

How to use Jext epipen

Answer 25

``` Remove yellow cap Grip device needle end is black Administer injection, hold for 10s Remove device and massage for 10s Phone ambulance Second dose after 5 mins ```

Question 26

Types of allergic rhinitis

Answer 26

Seasonal, hay fever Perennial, house dust mite allergy Occupational

Question 27

Allergic rhinitis presentation

Answer 27

Runny, blocked and itchy nose Sneezing Itchy, red and swollen eyes

Question 28

Allergic rhinitis triggers

Answer 28

Tree pollen or grass | House dust mites and pets

Question 29

Management of allergic rhinitis

Answer 29

``` Avoid trigger Hoover Stay indoors during high pollen counts Minimise contact with pets Oral antihistamines Nasal corticosteroid sprays: fluticasone, mometasone Nasal antihistamines ```

Question 30

Non-sedating anti-histamines

Answer 30

Cetirizine Loratadine Fexofenadine

Question 31

Sedating antihistamines

Answer 31

Chlorphenamine (piriton) | Promethazine

Question 32

Cows milk protein allergy

Answer 32

``` Typically affects <3 years IgE mediated (reaction occurring within 2 hours) or non-IgE mediated (over several days) ``` Risk factors: formula-fed babies, personal or FH of other atopic conditions

Question 33

Cows milk protein allergy presentation

Answer 33

Presents before 1 year of age Apparent when weaned from breast milk to formula milk Bloating and wind Abdominal pan D/V Allergi symptoms in cows milk protein allergy but not cows mill intolerance

Question 34

Management of Cow’s milk protein allergy

Answer 34

``` Breast feeding mothers should avoid dairy Hydrolysed formulas: proteins broken down Elemental formulas (amino acids) Every 6 months try infants on milk ladder ```