Allergy Flashcards
define allergy.
allergy is a type 1 hypersensitive disorder of the immune system
describe the pathophysiology of allergy.
sensitisation to something which is harmless -
plasma cells produce IgE which bind to mast cells
re exposure to this substance causes mast cells to degranulate and release histamine, leurkotriens, prostaglandins and chemotactic factors
these produce smooth muscle constraction, vasodilation, vascular permeability, leukocyte infiltration esp eosinophils
what is the time frame when is considered a late allergic response?
2-4 hours after exposure
what is allergic rhinitis?
allergic inflammation of the nasal airways
occurs when allergen in inhaled by an individual who has a sensitisation
what are the risk factors for allergic rhinitis?
atopy family history alterations in exposure to infectious diseases in childhood environmental pollution allergen levels dietary changes
what are the immediate symptoms of allergic rhinitis?
sneezing
itch
nasal blockage
rhrinorrhoea
what are the late symptoms of allergic rhinitis?
chronic obstruction
hyposmia
hyperreactivity
what investigations are used to diagnose allergic rhinitis?
serum specific IgE (RAST test) skin test total serum IgE nasal allergen challenge nasal cytology
what is the treatment for allergic rhinitis?
avoid allergen pharmacological; - topical intranasal steroid - systemic steroids - anti histamines - sodium cromoglicate - allergen immunotherapy - anti IgE
what are the classifications of allergic rhinitis?
intermittent or persistant
mild or moderate/severe
what is defined as intermittent and persistent rhinitis?
symptoms < 4 days per week or < 4 consecutive weeks
symptoms >4 days per week or >4 consecutive weeks
what is defined as mild and moderate/severe?
mild - normal sleep, no impairment of activities, work/school, symptoms persist but not troublesome
sleep disturbance, impairment of activity, school/work, troublesome symptoms
what do you have to be aware of when doing a skin test?
up to 15% are false positives
what are the levels of IgE which indicate negative or very high sensitivity in the RAST test?
<0.35 kU/L = negative
>100 = very high sensitivity
what are the risk factors for allergic reactions such as asthma, eczema and food allergies?
host factors - hereditary, race, age
environmental - pollution, alterations in exposure to infectious diseases in childhood, allergen levels, dietary changes
occupational - flour, latex, wood dust
