paediatric allergy

Question 1

IgE mediaed allergy pathophys

Answer 1

allergen prested to T cell
B cell activated
bind to mast cells
sensitisation

Question 2

mast cell exposed to allergen

Answer 2

bursting of mast cell releases inflammatory mediators

exposure to allergen

Question 3

mast cell degranulation

Answer 3

rapid release and onset of symptoms
histamine, tryptase, hydrolase

later realease of inflammatory mediators - prostaglandins, leukotrienes, cytokines

Question 4

what does histamine cause

Answer 4

• bronchial smooth muscle contraction
• vasodilation
• separation of endothelial cells (hives)
• pain and itching

Question 5

genetic influence to allergy

Answer 5

parental atopy (maternal)
concordance for allergy in twins

Question 6

hygiene hypothesis

Answer 6

too clean

children in farmyard environments less allergies/sensitisation

Question 7

is it allergy?

Answer 7

rapid onset
histamine mediated reactions
urticaria, erythema, andioedema, pallor/sweating, wheeze
improvement with antihistamines
relatively quick resolution of symptoms

Question 8

what caused the reaction?

Answer 8

food
environmental allergen 
drug
sting/bite
idiopathic

Question 9

common food allergies

Answer 9

cows milk 
hen's egg
peanuts
tree nuts e.g. walnuts
soya
wheat
fish 
sesame

Question 10

mild/moderate reaction

Answer 10

angioedema (not involving airway)

urticaria and rash

Question 11

severe reactions

Answer 11

andioedema of airway (stridor)
bronchospasm
hypotension

Question 12

supporting evidence that it is an allergy

Answer 12

prev reactions
atopy
FHx
response to Rx
co-existing asthma

Question 13

allergy investigations

Answer 13

skin prick testing
specific IgE - blood test
oral food change

Question 14

skin-prick testing pros

Answer 14

easy to do
non-invasive
immediate results - 20min
negative SPT very likely not allergy

Question 15

skin prick testing cons

Answer 15

stop antihistamine 48hrs prior
broken skin 
theoretical risk of reactions
dermatographism 
over-interpretation +ive results
avoid random tests

Question 16

specific IgE pros

Answer 16

no need to stop antihistamines

no risk of reactions

Question 17

specific IgE cons

Answer 17

expensive
invasive
delay in obtaining results
less sensitive and specific than SPT
highly unreliable results in eczema

Question 18

oral food challenge

Answer 18

day case procedure
gold standard
what actually happens upon contact or ingestion?

Question 19

invenstigating urticaria and angioedema

Answer 19

urticaria only with no trigger - none, consider SPT/IgE is sus food/environmental trigger

angioedema only - look for hereditary angioedema C4 and C1 esterase inhibitor

rarely: FBC, urinalysis, ESR, LFT, coeliac screen, TFT

Question 20

treatment of allergies

Answer 20

avoid triggers
H1 antihistamine
preventative: high dose antihistamines 
leukotriene antagonist
corticosteroids
tranexamic acid 
anti IgE monoclonal antibody (omalizumab) in kids >7yrs

Question 21

anaphylaxis features

Answer 21

laryngeal oedema
hypotension
collapse
bronchospasm
feeling of impending doom
onset usually in mins

Question 22

anaphylaxis onset of symptoms

Answer 22

within 60mins

later the onset the less severe the attack

Question 23

risk factors for anaphylaxis

Answer 23

poorly controlled asthma
stress
exercise
viral infection
alcohol

Question 24

adrenaline pen

Answer 24

adult 0.3mg, junior 0.15mg

1st line rx anaphylaxis
early use assoc with better outcomes

Question 25

potential interaction between adrenaline pen and …

Answer 25

b-blockers and tricyclics

Question 26

adrenaline

Answer 26

reversed peripheral vasodilation 
inc peripheral vasc resistance
improve BP and coronary perfusion 
decrease angiodema
cause bronchodilation
dec release inflammatory mediators

Question 27

who gets adrenaline pen

Answer 27

• suffered severe systemic reaction
• allergen not easily avoidable
• high-risk allergens e.g. nuts with other risk factors e.g. asthma
• reaction to trace amounts trigger
• continuing risk anaphylaxis
• idiopathic anaphylaxis
• signif co-factors e.g. asthma

Question 28

mangament options

Answer 28

allergen avoidance
anti-histamine
adrenaline injectors
dietary advice
optimise asthma control

Question 29

risk factors for nut allergy

Answer 29

eczema - transcutaneous sensitisation 
filaggrin mutations
eczema creams containing peanut oil
egg allergy 
asthme 
teenagers and young adults - risk taking, alcohol

Question 30

oral allergy syndrome

Answer 30

cross reactivity of tree/plant pollens and foods

mainly oral symptoms- itching, mouth swelling, tongue discomfort

peeling or cooking often reduces symptoms

Question 31

egg allergy

Answer 31

usually mild and benign but can be severe
many grow of it by 5yrs

tolerate well cooked/baked egg first and raw egg last

Question 32

management of egg allergy

Answer 32

avoidance
re-introduction
egg ladder

Question 33

IgE mediated cows milk allergy

Answer 33

rapid onset
histamine based reaction
vomiting, occasional diarrhoea
can be identified by SPT or SpIgE

Question 34

non IgE mediated cows milk allergy

Answer 34

not histamine based

diarrhoea, vomiting, irritable, infantile eczema, bloating, bleeding PR

improves with withdrawal of milk protein

Question 35

management of IgE mediated cows milk allergy

Answer 35

• maternal avoidance of cow’s milk
• Ca and VitD supplement
• EHF formula
• AA formula if not tolerated
• soya milk >1yr

Question 36

management of non-IgE CMA

Answer 36

• maternal avoidance of cow’s milk
• Ca and VitD supplement
• EHF formula
• AA formula if not tolerated
• soya milk >1yr