allergy

Question 1

describe the pathophysiology of an IgE mediated

Answer 1

rapid release of:
histamine, Tryptase, Hydrolase
-rapid onset of symptoms

LATER imflammatory mediators released: prostaglandins, Leukotrines, PAF, Cytokines

Question 2

effect of histamine?

Answer 2

• bronchial smooth muscle contraction
• Vasodilation
• Seperation of endothelial cells (resp for hives)
• Pain and itching

Question 3

what is the genetic influence towards allergy and atopy

Answer 3

maternal atopy

concordance for allergy in twins

no parent: 14%
one parent:30%
2 rents: 60%

hygiene hypothesis

Question 4

what is an allergy reaction?

Answer 4

IgE mediated

Question 5

features of an allergy?

Answer 5

rapid onset
histamine mediated
Urticaria
Erythema
angiodema
Pallor/sweating
wheeze
Improvement with anti histamines
relative quick resolution to symptoms

Question 6

what are common food allergens?

Answer 6

milk allergy
hen's egg
tree nuts
soya
fish
sesame
wheat

Question 7

what makes an allergy mild?

Answer 7

mild to moderate:
angiodema (not involving airway)
urticaria and rash

Question 8

what makes an allergy severe?

Answer 8

angiodema of airway (causing stridor)
bronchospasm
hypotension

Question 9

what investigation should you do if you suspect an allergy?

Answer 9

skin prick testing
specific IgE
Oral food challenge

Question 10

pros and cons of skin prick testing?

Answer 10

pros:
easy to perform
non invasive
cheap
immediate results- in 20 mins

cons:
stop antihistamines 48 hours beforehand
broken skin
theoretical risk of reaction
dermatogiphsm
over interpretation of positive results
avoid random tests

Question 11

specific IgE pro’s and cons:

Answer 11

pro's:
No need to stop antihistamines
no risk of reaction
expensive and invasive
less sensitive and specific than SPT
highly unreliable results in eczema

Question 12

what is the gold standard test for allergy?

Answer 12

oral food challenge

Question 13

when to do each tests?

Answer 13

just urticaria- none

suspected food allergy- SPT

angiodema only- (most common in teens with new presentation)look for C4 and C1 esterase inhibitor

Question 14

allergy treatment?

Answer 14

allergy avoidance
H1 antihistamine (2nd/3rd gen)
high dose antihistamine +/- amntihistamine
leukatrine antagnost
CCS (3-5 days)
tranexamic axid
anti IgE antibody (omalizumab) in children over 7

Question 15

anaphylaxis features?

Answer 15

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

almost invariable symptoms begin in 1 hour

Question 16

RF for anaphylaxis?

Answer 16

asthma (poorly controlled)
stress
exrecise
viral infection
alcohol

Question 17

how much adrenaline in an epipen? adult vs kid?

Answer 17

adult: 0.3mg
kid: 0.15mg

Question 18

what does adrenaline do in an anaphylactic reaction?

Answer 18

decrease angiodema
reverse peripheral oedema
increase peripheral vascular resistance
causes brachiodilation
decreases release of inflame mediators
improves BP and coronary perfusion

Question 19

RF for peanut allergy?

Answer 19

eczma
Filaggrin mutation
Eczema creams containing peanut oil
egg allergy
asthma
teens and young adults-risk taking, alcohol

Question 20

what is oral allergy syndrome?

Answer 20

kid allergic to fruit and veg only some of the time

from cross reactivity of tree/plant pollen and foods

give them antihistamine

-usually have history of hayfever

Question 21

egg alleergy features?

Answer 21

67% grow out of it by 5
can tolerate cooked egg the best, raw the least
usually mild and benign but can be severe

Question 22

what is the management of an egg allergy?

Answer 22

avoidance
re-introduction
egg ladder: 1. well cooked, 2. lightly cooked, 3. raw

Question 23

milk allergy features?

Answer 23

rapid pnset
histamine based reaction
symptoms may include b=voimitting and diarrhoea
diagnosis: SPT or SpIgE

Question 24

non IgE mediated milk allergy features/

Answer 24

not histamine based
baryon presentation; diarrhoea, vomitting, infantile eczema, bloating, PR bleeding

improves with withdrawal of milk protein

Question 25

ix of non IgE mediated milk allergy?

Answer 25

SPT
history
Specific IgE
therapeutic trial of exclusion under dieticians review

Question 26

management of milk allergy (some for IgE and non IgE)?

Answer 26

maternal avoidance of cows milk (if breastfeeding also need Ca and vit D supplememts)

EHF formula

if EHF not tolerate use AA formula

soya milk only if >1, or if others not tolerated