Allergies

Question 1

How common are allergies

Answer 1

20% of the population have allergies

Question 2

What is Atopy

Answer 2

an inherited tendency for an exaggerated IgE antibody response to common environmental antigens.

• positive skin rick to one or more allergens
• family hx of allergic disorders

Question 3

If a patient is allergic to peanuts what are other allergies should you consider in them.

Answer 3

50% of patients will have an allergy to tree nuts as well - walnuts, and almonds.

Question 4

If a patient is allergic to latex what other allergens may they have

Answer 4

they may have sensitivity to certain fruits - banana, avocado or kiwifruit

Question 5

What are the common ways that an atopic patient will manifest an allergic disorder

Answer 5

allergic rhinitis, asthma, atopic dermatitis, allergic gastroenteropathy

Question 6

What are the common sources of allergens (inhaled, food, other)

Answer 6

Inhaled - pollens, domestic animals, house dust mites mould spores, cockroaches
food - peanuts, fish, shellfish, milk, eggs, wheat, (NOT THE SAME AS FOOD INTOLERANCE.
other - drugs, allergens insect venoms, occupational

Question 7

How/when do atopic disorders present

Answer 7

immediate food hypersensitivity @ 0-1yrs
Atopic Dermatitis - (1-3yrs)
asthma @ 7-15yrs
allergic rhinitis 7-15yrs

Question 8

What are the four main types of allergic reactions

Answer 8

1. Type 1 - anaphylaxis / Immediate - IgE & mast cell mediated response to allergen eg. asthma
2. Type 2 - antibody to fixed antigen - Antibody (IgG/M) and complement eg autoimmune dx
3. Type 3 - immune complex disorders - Immune complexes e.g., vasculitits
4. Type 4 - cell mediated - T-Cell mediated (delayed type) e.g. contact dermatitis

Question 9

How does Type 1 Allergic Reaction Occur

Answer 9

Type 1 is a IgE & mast cell reaction. IgE is attached to the surface of mast cells and when they combine with a specific allergen causes a release by degranulations of chemical mediators (histamine, SRS-A etc) which then cause the symptoms.

Question 10

How does Type 2 Allergic Reaction occur

Answer 10

+++++++

Question 11

How does a food allergy present

Answer 11

Often in infancy and childhood
Main symptoms may be severe urticarial type reactions through to gastrointestinal symptoms such as - anorexia, nausea, vomiting, spitting up food, colic, diarrhoea, failure to thrive

Question 12

what are the two types of food allergy?

Answer 12

immediate (within 2hrs), delayed (up to 24-48hrs post)

Question 13

What is the difference between and intolerance and a food allergy

Answer 13

???????

Question 14

what are some clinical features of an IgE mediated food reaction

Answer 14

urticaria - facial or generalised
dizziness and confusion
wheexe
itchy, runny, nose and eyes
itchy throat
flushing or blotchiness/pallor (if severe)
angiodema of face and airway
vomiting, diarrhoea and abdo colic
usually in infants and toddlers

Question 15

When does food allergies normally resolve by?

Answer 15

5-7yrs

Question 16

what are the 3 big causes of food allergies?

Answer 16

Cow’s milk, eggs, peanuts

Question 17

when is it ok to introduce eggs to children?

Answer 17

avoid until 2years (including in cakes etc) then introduce cautiously - e.g. in cakes
all vaccines are safe (MMR has a minuscule amount)

Question 18

how do you test for allergies

Answer 18

Skin prick testing is first line - neg test is useful for excluding an IgE mediated allergy
RAST blood test to detect serum specific IgE ( expensive therefore done when - skin prick and Hx not adding up, extensive Eczema, dermographism, infants and very young children, immunotherapy work up)

Question 19

What drug options are there for allergy control?

Answer 19

Antihistamines (H1/H2 receptor antagonists)
Adrenaline - emergency
sympathometics, some anticholinergics, steroids, sodium cromoglycate.

Question 20

when does hay fever usually develop (age)

Answer 20

50% have it by 15yrs and 90% by 30yrs

Question 21

How does Hayfever present

Answer 21

widespread itching (nose, throat and eyes) is common however those with perennial rhinitis rarely have the eye and throat involvement (more just sneezing and watery rhinorrhea, they are more likely to develop nasal polyps.

Question 22

What are treatment options fro hay fever (seasonal allergic rhino conjunctivitis)

Answer 22

1. Antihistamine (oral - not much use in vasomotor rhinitis, intranasal - rapid action, opthalmic)
2. decongestants (topical or oral - get rebound congestion from topical)
3. sodium cromoglycate (intranasal - pwder, spray, opthalmic drops for conjunctivitis)
4. Corticosteroids (intranasal - not so effective for non-eosiniphilic vasomotor rhinitis, oral - very effective if other methods fail, opthalmic drops for allergic conjunctivitis)