3 Food Allergy- Assessment and Diagnosis Flashcards
Why are allergies associated with significant morbidity?
Define ‘allergy’.
Immunological mechanism leading to disease
= immunological hypersensitivity - leading to variety of different diseases
Can be IgE mediated or non-IgE mediated
What is an allergen?
Any substance stimulating production of IgE or cellular immune response
Usually a protein but can be carbohydrate
What is sensitisation (in terms of allergies)?
Production of IgE antibodies after repeated exposure to an allergen
Define anaphylaxis.
Serious allergic reaction
Bronchial, laryngeal and cardiovascular involvement
Rapid onset
Can cause death
Define atopy.
Tendency to produce IgE antibodies in response to ordinary exposure to potential allergens (asthma, rhinitis, eczema, food allergy, hay fever)
How do each of the following allergies present?
- Hay fever (Allergic rhinitis)
- Allergic conjunctivitis
- Asthma
- Urticaria
- Insect allergy
- Drug allergy
How is a baby with gastro-oesophageal reflux treated?
- Feed thickener
- Antacid
What is the commonest food allergy in infants?
By what age will in present? Why is it hard to pick up?
Commonest food allergy: Milk
Always presents by 12 months of age (symptoms can be many weeks after first ingestion)
Treated as GORD first? so difficult to pick up
What are the 2 types of presentation for a milk allergy in infants? Explain why.
What are the 14 major food allergens (EU)?
- Celery
- Peanuts
- Nuts
- Soya
- Cereals w./ gluten
- Fish
- Lupin (a flour)
- Milk
- Molluscs
- Mustard
- Sesame seeds
- Sulphur dioxide (in raisins, dried apricots)
- Crustaceans
- Eggs
Differentiate between a food allergy and food intolerance.
Food intolerance= adverse responses to foods that do not involve an immune response
Food allergy- involves an immune response
Differentiate between IgE mediated and non-IgE mediated food allergies in terms of:
- Time for symptom onset
- Common foods
- Presenting age
Differentiate between the signs and symptoms that might be seen with IgE-mediated food allergies and Non-IgE mediated food allergies.
Give 4 different phenotype presentations for immediate onset (IgE-mediated) food allergies. (4)
Give 4 different phenotype presentations for delayed onset (Non- IgE-mediated) food allergies. (4)
Most allergens are proteins. Why is this significant for cross-reactive food allergens?
Most proteins in cow’s milk= also in goats milk so patient can’t have either
When diagnosing a food allergy, what do we need to consider in the history and examination?
What tests can be done to diagnose a food allergy? (determine presence of sensitivity not allergy)
How do we select which tests to do?
- Skin prick tests
- response of skin mast cells to allergens
- Immunoassays to detect allergen-specific IgE
- IgE circulating in blood
Positive predictive thresholds developed for common allergens
Test selection done to avoid false positives:
- Clinical history
- Possible cross-reactivity
- Targeting likely antigens
