Allergies Flashcards
What percent of kids are affected by food allergies? What type of mediated rxns?
- 6-8%
- IgE (anaphylaxis) or non-IgE mediated rxns
IgE mediated rxns characteristics?
- typically rapid in onset (occur w/in minutes)
- skin
- GI tract
- respiratory tract
- anaphylaxis
8 most common sources of IgE mediated rxns (90%)
- cows milk
- eggs
- soybean
- wheat
- peanuts
- tree nuts
- fish
- shellfish
Which of the 8 most common sources of IgE mediated rxns usually (80%) resolve by age 5?
- cow’s milk
- eggs
- soybean
- wheat
Which of these common sources of allergies are usually lifelong?
- peanuts
- tree nuts
- fish
- shellfish
Characteristics of a non-IgE mediated rxn?
- occurs hours to days after exposure
- typically in infants
- can present as chronic skin conditions or most commonly manifests as GI sxs:
proctitis/proctocolitis
enteropathy
enterocolitis
Sxs of food induced allergic rxn (IgE and non-IgE mediated)?
- cutaneous: erythema, pruritus, urticaria, angioedema
- ocular: pruritus, conjunctival erythema, tearing, periorbital edema
- upper respiratory: nasal congestion, pruritus, rhinorrhea, sneezing, laryngeal edema, hoarseness, dry cough
- lower respiratory: cough, chest tightness, dyspnea, wheezing, intercostal retractions
- GI oral: angioedema of lips, tongue, or palate, oral pruritus, tongue swelling
- lower GI: nausea, colicky abd pain, reflux, vomiting, diarrhea
- CV: tachycardia (occasionally bradbradia cardia in anaphylaxis), hypotension, dizziness, fainting, LOC
Dx of food induced allergies?
- Hx
- physical
- skin prick test, allergen specific serum IgE, oral food challenge
- pts with large wheals from skin prick test or with high serum specific IgE are likely to have food allergy
- parent and pt reports of food allergy should be confirmed with testing as mult studies demonstrate 50-90% of presumed food allergies are not allergies
Tx of food induced allergies?
- avoidance
- epi-pen for tx for anaphylaxis
What sxs can be assoc with food allergies?
- atopic dermatitis
- acute urticaria
Relationship b/t atopic dermatitis (eczema) and food allergies?
- food allergy has been reported in up to 35% of pts referred to an allergist or derm for atopic dermatitis
- consider eval in infants and children with moderate to severe atopic dermatitis or if there is a hx of exacerbation when eating specific foods
- if food allergy is dx, the atopic dermatitis often improves after dietary elimination of that food
Relationship b/t acute and chronic urticaria with food allergies?
- the causes of acute urticaria vary and include infection, drug rxn, and food allergy
- acute urticaria is common sx present with food allergy
- in contrast, chronic urticaria is rarely related to food allergy
- food allergy testing is rarely indicated for chronic urticaria since most cases are idiopathic
What nasopharyngeal sxs occur with food allergies?
- acute rhinitis (typically assoc with other orpharyngeal sxs such as pruritus of throat and angioedema)
- chronic rhinitis is NOT a manifestation of food allergy
Most appropriate test in initial assessment of food allergy? Test results?
- serum specific IgE testing or skin prick testing
- a positive rxn is a wheal at least 3 mm greater than negative control
- neg predictive value is greater than 95% while the positive predictive value is less than 50%, therefore there are many false positive results
- antihistamines should be d/c prior to testing
- testing can’t be performed on skin with extensive eczema/rash or in pts with dermatographia
What is impt to remember about serum specific IgE testing?
- detection of serum IgE to specific allergens
- all positive and neg tests (skin and serum tests) need to be correlated with pts clinical hx
- a + test alone doesn’t make the dx of clinical food allergy (evidence of sensitization: immunological response)
Gold std for dx of food allergy?
- a double blind, placebo controlled food challenge. Open challenges are generally used in most clinical settings
- pts may benefit from oral food challenge if they have borderline test results or if false + or - is suspected based on clinical hx
- may prevent unjustified food elimination from diet
Oral food challenge process?
- pt given gradually increasing amt of suspected food allergen over a time period of hours to a day
- process requires close medical supervision
Atopy patch tests use?
- currently used to d delayed hypersensitivity T cell mediated rxns such as contact dermatitis
- atopy patch testing for IgE mediated food allergy isn’t recommended
What are variables in the skin tests and specific IgE tests?
- each allergen may have diff normal IgE level and wheal diameter
- also dependent on age of child
- cutoff value is the concentration of specific IgE for particular food allergen that is 90% predictive of clinical rxn to food
- increasing levels of specific IgE and wheal response to SPT correlate with allergy but don’t predict severity of rxn
Why should food be continued on a regular basis if positive IgE results with no rxn while consuming food?
- because testing indicates that the child is sensitized to the allergen, a prolonged absence of the food from the diet could lead to clinical sxs upon re-exposure
Tx of food allergies?
- children should be instructed not to share or trade food with others and to notify adults if they eat something that may contain the food to which they are allergic
- epi-pen auto injector (should be given IM in thigh) 0.15 mg of 1:1000 epi for 15-30 kg (33-66 lbs), and 0.3 mg of 1:1000 epi for anyone over 30 kg
What is pollen-food allergy syndrome (PFAS) or oral allergy syndrome?
- IgE-mediated rxn that affects oropharynx
- occur from cross-reactivity b/t proteins present in pollens and those in fruits and veggies
- pts develop tingling and itching of lips, tongue, and palate when eating certain raw fruits and veggies
- systemic signs are very rate
- sxs don’t occur when fruit or veggie is cooked
- syndrome affects up to 50% of adults with allergic rhinitis secondary to pollens
What fruits and veggies have a x-reactivity with birch pollen allergy?
- apples, plums, peaches, nectarines, cherries, almonds
What fruits have a x-reactivity with ragweed pollen?
- melons, bananas, and tomatoes
What fruits have a x-reactivity with grass pollen allergy?
- melons and kiwi fruit
How do you dx PFAS?
- confirmed through skin prick testing to fresh foods and pollen and also with oral food challenges
- oral challenges are rarely necessary
Tx of PFAS?
- sxs can sometimes be controlled with antihistamines
- pts should avoid consumption of raw food product that produced sxs: may continue to eat specific food if it is cooked
- any pt who has hx of systemic sxs should strictly avoid the foods in all forms and carry an epi auto-injector
Who is more at a higher risk for fatal food-induced anaphylaxis? young kids or teens?
- teens
- dose provoking sxs in peanut-allergic pts decreases with age, which may in part contribute to the difference in risk
- studies have shown that adolescents have poor understanding of when food allergy rxns are severe and wehn epi is indicated
How common is accidental exposure to peanuts and tree nuts?
- high as 48%
- 54% of adolescents admit to purposefully eating potentially unsafe food
Which food allergy is more common in adults than children?
- shellfish
Most common food allergies in children?
- milk
- egg
- peanut (second most common food allergy in adults but is still more common in children - affects 0.8% of young kids - 0-5 yrs)
Most common food allergies in adults?
- shellfish
- peanut
- tree nut
- allergies to tree nuts and fruits are more prevalent among adolescents and adults than children
Epidemiology of allergic rhinitis?
- peak prevalence: 14-25 yrs
- 80% develop sxs befpre age 20
- 10-30% of pop affected
- 30-50 mill Americans affected
- loss of 3.5 million work days and 2 million school days
- cost more than 15 bill annually
Sxs of allergic rhinitis?
- sneezing
- rhinorrhea
- nasal congestion
- itching of eyes, nose, palate, and ear canals
- postnasal drip, cough
- irritability
- fatigue (not just from meds)
How can AR have a significant impact on quality of life and cognitive fxn?
- sleep disordered breathing
- fatigue
- general malaise
- cognitive and psych issues in kids: ADHD, lower exam scores in peak pollen season, poor concentration, impaired athletic performance and low self esteem
What diseases are assoc with allergic rhinitis?
- otitis media and eustachian tube dysfxn
- sinusitis
- asthma
- sleep related breathing disorders
DDx of allergic rhinitis?
- viral URI
- chronic sinusitis
- adenoidal hypertrophy
- septal deviation
- turbinate hypertrophy
- fbs
- choanal atresia
- nasal polyps
- immunodeficiencies
- CSF leak
- tumors
Physical presentation of AR?
- allergic salute: transverse crease across nasal bridge
- allergic shiner: dark swollen, infra-orbital tissue
- Dennie morgan lines: infra-orbital creases due to edema and thickening of skin
- conjunctival chemosis
- cobblestoning in throat and under eyelid
AR - manifestations in nose?
- common allergic rxn that causes inflammation in lining of nose
- inflamed nasal lining (appears pale, boggy blue)
- postnasal drip
- clear nasal d/c
Dx or AR?
- suggestive hx
- supportive exam
- identify specific IgE
Diff b/t sensitization and allergy?
- both skin testing and serum IgE testing detect sensitization - presence of specific IgE to an allergen
- Allergy is a clinical syndrome with sxs combined with evidence of sensitization (Positive skin or serum test)
Tx of AR?
- enviro control
- pharm:
antihistamines, decongestants, nasal steroids, anticholinergics, mast cell stabilizers, ocular meds, leukotriene modifiers - immunotherapy
Classification of AR?
- intermittent mild: less than 4 days a week, or less than 4 weeks, mild - normal sleep and daily activities, normal school and work, and no troublesome sxs
- intermittent mod-severe
- persistent mild
- persistent moderate-severe: more than 4 days/week, and more than 4 weeks, will have one or more of the following: abnormal sleep, impairment of daily activities, sports, leisure, problems caused at work and school, troublesome sx
Approach to kids under 2 with AR?
- uncommon
- in all pts avoidance therapy is most effective 1st line therapy
Meds approach for kids younger than 2?
- no first gen antihistamines (worried about respiratory depression and death)
- cromolyn nasal spray
- 2nd gen antihistamine: ceterizine, fexofenadine (kids greater than 6 mo)
- intranasal glucocorticoids if severe sxs and no response to above therapies (too much systemic absorption in this young of kids)
Med approach for kids older than 2 with mild or episodic sxs?
- cetirizine, loratidine, or fexofenidine: 2-5 hrs prior to exposure
- or intranasal topical antihistamine (azelastine: older than 5, and olopatidine for kids older than 12)
- intranasal glucocorticoid: more effective antihistamines
- or intranasal cromolyn 30 min prior to exposure
Med management for kids older than 2 with persistent or severe sxs?
- intranasal glucocorticoid
- topical nasal antihistamine
- oral antihistamine
- decongestant
- start with 1st med and add on in this order if needed for persistent sxs
Intranasal glucorticoids for kids?
- mometasone (nasonex): kids 2 and older
- fluticasone furoate (veramyst): kids 2 and older
- fluticasone propionate (flonase) for kids 4 and older
Topical nasal antihistamines in kids?
- Azelastine (Astelin) for kids older than 5
- Olopatidine (patanase) for kids older than 12
- combo azelastine and fluticasone (dymista) older than 12
Meds for AR with allergic conjunctivitis?
- intranasal glucocorticoid + topical ophthalmic antihistamine drops
- combo less drying than oral antihistamines
Meds for AR with asthma? BBW?
- leukotriene modifier (inhibits mast cell degranulation):
monteleukast (singulair)
approved for use in kids as young as 6 months - SEs: are depression and suicidal ideations in adults (BBW )
- more common in kids: hyperactive and emotional, anxiousness
