Food allergy/intolerance

Question 1

What is somatosensation disorder?

Answer 1

Hisotry similar to that of allergy but psychological rather than pathological cause
Can cause restrcitive/unhealthy eating

Question 2

What does the skin sensitisation theory of allergy suggest about what the two main contributors to developing a food allergy are?

Answer 2

Break in infants skin - eczema/skin infection allows allergens from environment into skin - react with immune system
Child does not have contact form GI tract and absence of GI exposure to the allergen

Question 3

What is the skin sensitisation theory of allergy?

Answer 3

Allergens enter through skin recofnised as foreign and harmful -> sensitised. When encountered again -> full immune repsonse (allergic reaction)

Question 4

What can help prevent allergies from developing?

Answer 4

Regular GI tract exposure
Preventing allergens entering through skin barrier

Question 5

When do babies start to be weaned?

Answer 5

6 months

Question 6

What criteria is used to classify allergies?

Answer 6

Cooms-Gell classification

Question 7

What antibodies are ass with type I allergic reaction?

Answer 7

IgE

Question 8

How does type 1 hypersensitivity reaction cause an allergic reaction?

Answer 8

IgE -> mast cells and basophils release histamines and cytokines

Question 9

What allergic reaction causes an immediate reaction to food eg anaphylaxis?

Answer 9

Type I

Question 10

What happens in a type 2 hypersensitivity reaction?

Answer 10

IgG and IgM antibodies react to allergen -> complement system

Question 11

What type of hypersensitivity reaction causes haemolytic disease of the newborn and transusion reactions?

Answer 11

Type 2 - complement system, IgG, IgM

Question 12

What type of hypersensitivity reaction causes SLE, rheumatoid arithritis and Henoch-Schonlein pupura?

Answer 12

Type 3 - immune complexes accumulate and cause damage to local tissues

Question 13

What type of hypersensitivity reaction causes organ transplant rekection and contact dermatitis?

Answer 13

Type 4 - cell mediated T lymphocytes

Question 14

What conditions are Type 3 HS reactions ass with>

Answer 14

Autoimmune

Question 15

How does type 4 HS reaction cause rejection?

Answer 15

Innapropriate activation of T cells -> inflamamtion and damage to local tissues

Question 16

What are important areas to cover in an allergen history>

Answer 16

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

Question 17

Three ways to investigate allergy

Answer 17

Skin prick testing
RAST testing - IgE
Food challenge

Question 18

What do skin testing and RAST actually assess?

Answer 18

Sensitisation NOT allergy

Question 19

Whatis gold standard for diagnosing food allergy and why?

Answer 19

Food challenge
Measures IgE therefore actual allergic reaction not just sensitisation

Question 20

What controls are used with antigen in skin prick testing?

Answer 20

Water and histamine dots also placed on skin

Question 21

How get infor from skin prick test?

Answer 21

Size of wheels after 15 minutes

Question 21

How get infor from skin prick test?

Answer 21

Size of wheels after 15 minutes

Question 22

What condition is patch testing most helpful in?

Answer 22

Allergic contact dermatitis in response to specific allergne
NOT food allergies
Assess after 2-3 days

Question 23

Why can RAST testing not be used for allergen specific testing in atopic condtiions?

Answer 23

Results come back positive for everything test

Question 24

What does RAST measure?

Answer 24

Total and allergen specific IgE quantities in blood

Question 25

What is important about how conduct food challenge?

Answer 25

In specialised unit with very close monitoring

Question 26

Management of food allergies

Answer 26

Establish correct allergen essential Avoidance of that allergen and foods that trigger reactions Prophylactic antihistamines if exposure inevitable Adrenalin autoinjector if at risk of anaphylaxis

Question 27

What is immunotherapy?

Answer 27

Lengthy process gradually exposing patients to allergens over months - aim of reducing reaction to certain foods or allergnes

Question 28

What do you treat people with after exposure? (non anaphylaxis)

Answer 28

Antihistmaines eg cetirizine Steorids eg oral prednisolone, topical hydrocortisone or IV hydrocortisone

Question 29

What age group is affected by cows milk protein allergy?

Answer 29

Children under 3 years

Question 30

How long does it take for an IgE mediated vs non-IgE mediated reaction to cows milk to occur?

Answer 30

IgE - rapid reaction, occurs within 2 hours non-IgE - slowly over several days

Question 31

Lactose intolerance vs cows milk intolerance vs cows milk allergy

Answer 31

Lactose intolerance - intolerance to the sugar lactose in milk Cows milk intolerance - same GI symptoms as allergy, no allergic sy,ptoms Cows milk allergy - allergic to proteins in cows milk

Question 32

Which babies is cows milk allergy more likely in?

Answer 32

Formula fed Personal or family hisotry of other atopic conditions

Question 33

When does cows milk allergy present?

Answer 33

Under 1 years

Question 34

GI problem

Answer 34

* Bloating and wind * Abdominal pain * Diarrhoea * Constipation * Vomiting (effortless) * Blood or mucus in stool * Colicky/irritable * Feed refusal

Question 35

Allergic symptoms in response to cows milk protein

Answer 35

Urticarial rash (hives) Angio-oedema - facial swelling Cough or wheeze Sneezing Watery eyes Eczema

Question 36

How to diagnose cows milk allergy?

Answer 36

Full history and exam Skin prick testing to support but not always necessary

Question 37

Management of cows milk allergy

Answer 37

Breast feeding mothers avoid dairy products Replace forumla with hydrolysed formulas Severe - elemental formulas of base aas eg neocate

Question 38

How often should a child be tried on the first step of the milk ladder?

Answer 38

Every 6 months after one year old