Allergies

Question 1

Anaphylaxis - state the following:
- Pathophysiology
- Presentation
- Management (immediate and after event)

Answer 1

Pathophysiology:
- Severe type 1 hypersensitivity reaction to allergen
- IgE stimulates mast cells to release overwhelming amounts of histamine (mast cell degranulation)

Presentation:
- Rash / urticaria
- Itching
- Facial swelling
- SOB
- Wheeze
- Stridor
- Tachycardia
- Dizziness / collapse
- Abdominal pain

Management (immediate and after event):
Immediate
- IM Adrenaline 500mcg 1:1,000 dose into antero-lateral aspect of the thigh (repeat dose after 5 minutes if no response)
- Use lower doses in children but at the same concentration (150mcg if 0-5 years, 300 if 6-11 years, normal dose thereafter)
After
- Education on how to manage triggers and spotting signs of anaphylaxis
- Ensure Adrenaline auto-injector and correct technique

Question 2

Outline the term allergy in broad terms

Answer 2

A tendency to have a hypersensitivity reaction of the immune system to allergens

Question 3

Outline the term atopy in broad terms

Answer 3

Predisposition to having hypersensitivity reactions to allergens e.g. eczema, asthma, hay fever, allergic rhinitis, food allergy

Question 4

Give some examples of hypersensitivity reactions

Answer 4

• Hay fever (allergic rhinitis)
• Eczema
• Asthma
• Food allergies
• Animal allergies

Question 5

Outline the 3 main ways to test allergies

Answer 5

1) Skin prick test - tests sensitisation not allergy
2) RAST testing (blood tests for IgE) - tests sensitisation not allergy
3) Food challenge testing = gold standard

When tests sensitisation not allergy - notoriously unreliable and misleading
Food challenge testing = gold standard, however is resource and time intensive

Question 6

State 2 classes of medications that can be used to manage allergic reactions

Answer 6

1) Anti-histamines
2) Steroids
Work by dampening immune response to allergen

Can use Adrenaline in anaphylaxis

Question 7

Briefly outline cow’s milk protein allergy and how it differs from cow’s milk protein intolerance and also how it differs from lactose intolerance

Answer 7

Cow’s milk protein allergy:
- Hypersensitivity to the protein in cow’s milk
- Can be IgE mediated (reaction within 2 hours) or non-IgE mediated (reaction over days)

Affects infants and young children (under 3)

Cow’s milk protein allergy is an allergic reaction to a protein
It’s different from Cow’s milk protein intolerance, which is an intolerance to the protein, but does not present with any allergic-type symptoms e.g. hives, facial swelling.
It’s different from lactose intolerance, which is a reaction to a sugar (lactose).

Lactose intolerance does not involve the immune system as is not an allergic process.

Question 8

State how cow’s milk protein allergy might present

Answer 8

Occurs in infants and young children (under 3), but usually presents under 1 year old

Can occur when breastfeeding mother consumes dairy, or when weening baby from breastmilk, to formula or food containing milk

GI:
- Vomiting
- Bloating and wind
- Abdominal pain
- Diarrhoea
General allergic reactions:
- Hives
- Cough or wheeze
- Angio-oedema
- Eczema

Question 9

State how Cow’s milk protein allergy is investigated and managed

Answer 9

Investigations:
- Diagnosis made largely on history and examination
- Skin prick testing can be used to support diagnosis but is not always necessary

Management:
- Breastfeeding mothers should avoid dairy
- Replace formula with hydrolysed formulas

Most children will outgrow allergy by the age of 3
Every 6 months an infant can be tried on the first step of the milk ladder - overtime they should be able to progress

Question 10

State how an Epipen / Jext pen should be used in anaphylaxis

Answer 10

Epipen / Jext pen contain a single dose of Adrenaline

• Ensure holding the pen correctly (like a dagger)
• Remove safety cap
• Jab into anterolateral thigh until click is heard
• HOLD in thigh for up to 10 seconds
• Remove pen and rub the area