Paediatric food allergy

Question 1

pathophysiology of IgE mediated allergy?

Answer 1

allergen on class II MHC - T helper- IL - B cells

Question 2

T2 helper cells affect ?

Answer 2

B cells - Production of IgE

• mast cells - sensitisation to allergen

Question 3

Release of soluble mediators of mast cells? (4)

Answer 3

• histamine
• cysteine leukotrienes
• prostaglandins
• cytokines

Question 4

what cells do mediators affect (4)

Answer 4

• epithelial cells
  blood vessels
• smooth muscle
• fibroblasts

Question 5

mast cell degranulation? rapid secretions

Answer 5

histamine, tryptase, hydrolase

Question 6

what is secrete in the biphasic reaction

Answer 6

• prostaglandins
• cytokines
• leukotrienes
• PAF

Question 7

what does histamine do?

• what signs does it clinically show?

Answer 7

Smooth muscle contraction - wheezing

• vasodilation - flushing, hypotension - white pallor patches
• separation of endothelial cells - hives , oedema
• pain and itching

Question 8

genetic influence to allergy ?

what are the percentages?

Answer 8

• maternal atopy
• twins

neither parent = 14%, one part = 30%
both parents = 60%

Question 9

how to decide if it is allergy or not?

Answer 9

rapid onset

histamine mediated reactions

• improvement with antihistamines

Question 10

clinical signs of allergy (5)

Answer 10

angioedema, urticaria (raised skin lesions), erythema, pallor/sweating, wheeze

Question 11

what caused the reaction?

Answer 11

food

environmental

drug

sting/bite

idiopathic

Question 12

most common food allergens you get?

Answer 12

milk

hen’s egg

peanut

tree nuts

soya

wheat

fish

sesame

Question 13

how to work out hoe severe the reaction is - mild/moderate?

Answer 13

Angioedema - not involving airway ,

• urticaria and rash

Question 14

how to work out hoe severe the reaction is- severe

Answer 14

angioedema of airway - stridor

• bronchospasm
• hypotension

Question 15

what investigations are available? (3)

Answer 15

skin pick testing
specific IgE - blood test
oral food challenge

Question 16

first line investigation for allergy

Answer 16

skin prick testing

• non-invasive
• immediate results

Question 17

negative skin prick tests are a good predictor for?

Answer 17

negative IgE mediated food reaction in patients with anaphylaxis

Question 18

pitfalls of skin pick testing

Answer 18

stop antihistamines 48 ours prior

• broken skin
• risk of reactions
• dermatographism
• over interpretation
• avoid random tests

Question 19

positive test is?

Answer 19

3ml over the negative control

Question 20

Specific IgE testing

Answer 20

• no need to stop antihistamines
• expensive and invasive
• delay in obtaining results
• less sensitive and specific than SPT
• high unreliable with children who have eczema

Question 21

children with eczema have high levels of?

Answer 21

basal levels of IgE

Question 22

IgE egg, milk and peanut allergy kUA/L score at age 5

Answer 22

7
15
14

Question 23

specific IgE testing can cause interference from ?

Answer 23

high total IgE

Question 24

oral food challenge is the ?

Answer 24

gols standard test

- day case procedure

Question 25

urticaria and angioedema - chronic?

• what is more common to have on its own?

Answer 25

> 6 weeks

urticaria

Question 26

without urticaria - may be due to

Answer 26

C1 inhibitor deficiency

Question 27

investigation for urticaria on its own?

Answer 27

None

Question 28

possible food or Environmental trigger / investigations

Answer 28

skin testing

specific IgE

Question 29

Angioedema only -

Investigations?

Answer 29

hereditary
- teengers
C4 and C1 esterase inhibitor

Question 30

Rarely you may do what investigations?

Answer 30

FBC, urinalysis, ESR, LFT, coeliac screen, TFT, antithyroid

Question 31

Treatment of allergy

Answer 31

• triggers

H1 - antihistamine - 2nd/3rd generation

Question 32

Treatment of allergy
- acute episode?

• what can you add in?

Answer 32

high dose antihistamines
- leukotriene antagonist (montelukast)

corticosteroids (3-5 days)

Anti IgE monoclonal antibody (Omalizumab) > 7 years

Question 33

Angioedema - what can you use to treat

Answer 33

Tranexamic acid

Question 34

anaphylaxis involves

Answer 34

laryngeal - oedema - stridor

hypotension/collapse - - pallor

• bronchospasm
• feeling impeding doom

Question 35

clinical features of anaphylaxis

Answer 35

-20 % have biphasic reaction up to 8 hours later

Question 36

risk factors for anaphylaxis

Answer 36

ASTHMA - poorly controlled

• stress
• exercise
• viral infection
• alcohol

Question 37

Adrenaline pens - what is the adult and junior dose

Answer 37

0. 3 mg

0. 15mg

Question 38

First line treatment of anaphylaxis

Answer 38

adrenaline pen

Question 39

adrenaline pen can interact with?

Answer 39

bet blockers and tricyclics

Question 40

what does adrenaline do (6)

Answer 40

• reverses peripheral vasodilation
• inc peripheral vascular resistance
• improves BP and coronary perfusion
• decreases angioodema and inflammatory mediators
• causes bronchodialtion

Question 41

next 300 vs 150 - patient weight

Answer 41

300 > 30kg

150 - 15-30kg

Question 42

who needs an adrenaline pen?

Answer 42

those who have had severe reaction

• when allergy can’t be avoided
• high risk allergens , asthma risk factors