Food Allergies (Quiz 2) Flashcards Preview

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Flashcards in Food Allergies (Quiz 2) Deck (47):

Patients with diagnosed allergies should have one EpiPen cartridge
with them at all times T/F

False: TWO


Allergies to peanuts and shellfish are usually outgrown T/F 



Allergies can never improve or be outgrown T/F



Antihistamines can abort an anaphylactic allergic reaction T/F 



An allergy diagnosis is considered a disability and schools are

responsible for 504 plan needs T/F 



Patients with eczema are more likely to have food allergies T/F 




Primary care providers should diagnose food allergies T/F



How common are allergies?

  • •5% of children under the age of 5 years
  • •4% of teens and adults, on the increase
  • •More than 300,000 ambulatory-care visits per year for children <18
  • •Black and Asian children higher odds; lower odds of being diagnosed


Definitions: food allergy, food allergens, cross reactivity


  •  Food allergy:  Adverse health effect due to immune response from exposure to certain food
  •  Food allergens:  Specific components of food (typically proteins) that are recognized by allergen-specific immune cells and elicit immune reaction 
  •  Cross reactivity:  When an antibody reacts not only with the original allergen but also with a similar allergen


Immune mediated vs non-immune mediated food reactions


There are different types of reactions to food.  However, in order to be a food allergy, it must be immune mediated.  Lactose intolerance is not immune mediated, therefore, it is not a food allergy.  

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Why is it important to ID IgE mediated vs non IgE mediated reactions?

+ examples of non-IgE FAs


  • The main distinction in food allergies is between allergies caused by IgE mechanisms and food allergies caused by other mechanisms.  This is important because IgE mediated reactions can progress to anaphylaxis and must be identified and managed
  • Some examples of non-IgE or cell mediated food allergies:
    • Eosinophilic GI disorders
    • Dietary protein-induced disorders
    • Celiac disease
    • Atopic dermatitis

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Relationship Between Gut and Food Allergies

•Oral tolerance: immune unresponsiveness to harmless antigens

•Disruption of GI mucosal immune system alters normal state of oral tolerance

•Breakdown of oral tolerance-->food allergy


Pathophysiology of an allergic reaction


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Common food allergies in children vs teens and adults


  • ●These account for 90% of food allergy reactions
  • ●Common food allergies in children are milk, egg, wheat and soy allergies and they often resolve in childhood
  • ●Peanut, tree nut, fish and shellfish allergies can resolve, but are more likely to persist
  • ●The time course of FA resolution in children varies by food and may occur as late as the teenage years. A high initial level of sIgE against a food is associated with a lower rate of resolution of clinical allergy over time.

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Prevalence of allergies by age

peanut / shellfish / tree nut / milk / egg / wheat

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Cross reactivity chart

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Important HPI Qs for food allergies


•What are the symptoms?
•What food caused the symptoms? 
•Reaction to this food in the past?
•What quantity of food was ingested?
•Was the food baked or uncooked?
•How soon after eating the food did you experience symptoms?
•Were other factors involved such as exercise, alcohol, or aspirin/NSAIDS?
•What treatment was used?
•How long did the symptoms last?

Timing: IgE mediated reactions occur rapidly after ingestion.  Uncommonly, reactions up to two hours and beyond can also occur

It is more likely for a food that is rarely eaten to trigger an acute allergic reaction rather than a food that is a frequently eaten 

If a child has a reaction to a meal that was previously tolerated, think about whether or not the food was contaminated

IgE reactions can be triggered by small amounts of food proteins.  Threshold doses required to trigger a reaction vary

Some medications increase the rate of allergen absorption

Exercise induced anaphylaxis in adults

Reaction to food in the past?-severity of reaction is unpredictable




Symptoms of food allergy


  • combo of:  nausea, vomiting, cramping, diarrhea, flushing, pruritis, urticaria, swelling of the lips/face/throat, wheezing, lightheadedness, syncope.
  • A patient may present with one or two of these symptoms or more.  In children a classic presentation is vomiting and urticaria

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Past Medical History/Family History Qs for food allergies


  • •History of prior reaction to food?
  • •History of asthma, atopic dermatitis, or allergies?
    • •Children with food allergy are 2-4x more likely to have these conditions
  • •History of food aversions?
  • •Family history of asthma, allergies, atopic dermatitis?

Family history of atopy and the presence of AD are risk factors for the development of both sensitization to food and confirmed FA.

FA is associated with severe asthma.

In patients with asthma, the coexistence of FA may be a risk factor for severe asthma exacerbations. Moreover, food may be a trigger for exercise-induced anaphylaxis


PE for food allergies


  • •No findings are diagnostic of food allergy
  • •May have evidence of atopy
  • Skin: Urticaria, eczema, dermatographism, edema
  • HEENT: Rhinitis, rhinorrhea, conjunctival injection, periorbital edema, tearing
  • Respiratory: Wheezing, dyspnea, tachypnea, laryngeal edema
  • CV: Tachycardia or bradycardia, hypotension
  • GI: Abdominal tenderness, bloating


Differential Diagnoses for food allergies

  •  Immune reaction
  • ◦Allergy
  • ◦Asthma
  • ◦Atopic dermatitis
  • Non-immunologic adverse food reactions
  •  GI disorders
  • ◦structural abnormality
  • ◦carbohydrate malabsorption
  • ◦GERD
  •  Toxic reactions
  • ◦seafood
  • ◦food poisoning
  •  Intolerances
  • ◦pharmacologic agents
  • ◦flavorings and preservatives
  •  Psychologic reactions
  • ◦food phobia/aversion
  •  Accidental contaminations
  • ◦pesticides


Describe the skin prick test (SPT)


  • •Measures presence of IgE antibodies
  • •Results within 30 minutes
  • •Wheal=positive reaction
  • •Pros:  inexpensive, immediate results, performed in doctor’s office
  • •Cons:  false positives, antihistamines can interfere with results

Size of wheal not indicative of how allergic

No antihistamine for minimum 4 weeks

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Describe in vitro testing for allergies


  • •Measures presence of IgE antibodies to specific foods
  • •Provides information about the chance there is an allergy
  • •Used to be called RAST
  • •Pros:  test results are not affected by antihistamines, can be performed in people with extensive rashes 
  • •Cons:  results take several days, false positives

May have positive test to foods that do not cause actual reactions on exposure and may have negative tests to foods that do cause reactions

Neither IgE nor skin prick is diagnostic – suggestive along with clinical symptoms


What is the Oral Food Challenge


  • GOLD STANDARD for diagnosis
  • Ideally double blind placebo
  • •Conducted under supervision of allergist
  • •Start with small measured amounts
  • •If no symptoms, gradually increase dose
  • •If there are signs of a reaction, stop the food challenge
  • •Usually reactions are mild (flushing and hives)
  • •Pros:  Can rule out food allergy 
  • •Cons: Potential serious allergic reaction


What is the Food Elimination Diet?


•Avoid suspect foods
•Generally lasts 2-4 weeks
•Monitor symptoms  
•Gradually reintroduce problem foods 
•If inconclusive results-->oral food challenge




Tx of allergies

•First line treatment:  Allergen avoidance
•Learn how to interpret ingredients on food labels
•8 major allergens must be listed in plain English
•Advisory labeling not required
•Antihistamines for symptom management in non-severe reactions
•EpiPen for anaphylaxis
•Allergen-specific immunotherapy not recommended


Primary care mgmt of food allergies

•Serum tests for food-specific IgE
•Food diary
•Food elimination
•Prescribe an EpiPen
•Antihistamines for non-severe reactions

The generalist should take care not to impose dietary restrictions that put patients, particularly growing infants and children, at nutritional risk


Allergist mgmt of food allergies

•Serum and/or skin prick tests for food-specific IgE antibodies 
•Diagnostic elimination diets
•Physician-supervised oral food challenges

If an IgE allergy is suspected, refer to an allergist

The management of non-IgE mediated food allergy often requires the assistance of a gastroenterologist as well as allergist



what is Oral Allergy Syndrome


•Pollen-associated food allergy
•Localized IgE-mediated
•Symptoms:  Itching of lips, tongue, roof of mouth, throat with/or without swelling and/or tingling of the lips, tongue, roof of the mouth and throat


mgmt of oral allergy syndrome


•Mgmt: Cooking, baking, microwaving alters allergens

  • •Antihistamines?
  • •Subcutaneous immunotherapy (SCIT) not recommended
  • Spectrum – can be mild to anaphylaxis, may change over time. Always Rx epi pen
  • Cooking peanuts/nuts actually increases allergenicity so don’t recommend for peanut allergies!!


cross reactivity in oral allergy syndrome


•Patients usually tolerate the culprit food in various cooked forms. Cooking, baking, or even briefly microwaving raw fruits and vegetables is usually sufficient to alter the allergens that are responsible for PFAS.

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How a Kid Might Describe a Reaction

  • •This food is too spicy.“
  • •"My tongue is hot [or burning].“
  • •"It feels like something’s poking my tongue.“
  • •"My tongue [or mouth] is tingling [or burning].“
  • •"My tongue [or mouth] itches.“
  • •"It [my tongue] feels like there is hair on it.“
  • •"My mouth feels funny."
  • •"There’s something stuck in my throat.“
  • •"My tongue feels full [or heavy].“
  • •"My lips feel tight.“
  • •"It feels like there are bugs in there." (to describe itchy ears)
  • •"It [my throat] feels thick.“
  • •"It feels like a bump is on the back of my tongue [throat].“
  • •“There’s a frog in my throat.”


Anaphylaxis - What is it? Most common triggers


  • •Serious allergic reaction that is rapid in onset and may cause death
    • •involves systemic mediator release from sensitized mast cells and basophils
  • •Involvement of 2 or more body systems
  • •Under-recognized and under-treated
  • •Most common triggers for anaphylaxis: peanut, tree nut, milk, egg, fish, and shellfish
  • •Can occur with first exposure
  • •Asthma:
    • •important risk factor for death from anaphylaxis!


Timing of Anaphylaxis


Reaction can be: 

Uniphasic: occurs immediately after exposure and resolves with or without treatment within the first minutes to hours and then does not recur during that anaphylactic episode
Biphasic : includes recurrence of symptoms that develops after an apparent resolution of the initial reaction (usually occur about 8 hours after first reaction but can occur as much as 72 hours later)
Protracted: anaphylaxis episode that lasts for hours or days following the initial reaction

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s/s of anaphylaxis


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Diagnostic Criteria for Anaphylaxis


  • Acute onset of an illness (mins to hrs) with involvement of the skin, mucosal tissue, or both  
  • And at least one of the following:
  • -Respiratory comp
  • -Reduced BP or sxs end organ dysfunction
  • OR
  • Exposure to a likely allergen 
  • Plus 2 or more:
  • -Skin-mucosal sxs
  • -Respiratory compromise
  • -Reduced BP or associated sxs of endorgan dysfunction
  • -Persistent GI sxs
  • OR
  • Exposure to known allergen 
  • -PLUS low sys BP
  • or greater than 30% decrease from baseline

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Anaphylaxis: Initial Management


•Elimination of additional allergen exposure
•IM injection of epinephrine
•Call for help!!! (resuscitation team/call 9–1–1), should not delay use of epinephrine
•Placement of the patient in a recumbent position (if tolerated), with the lower extremities elevated
•Repeat EpiPen in 5 mins  if symptoms persist
•Once transferred to emergency facility
•IV fluids and vasopressors
•Oxygen, beta-2 agonists (albuterol)
•Observe 4-6 hours


1st line Tx for anaphylaxis

(know by age)


  • IM auto-injector or 1:1,000 solution
  • If weight>25 kg (55 lbs) use EpiPen – 0.3 mg per dose
  • If weight 10-25 kg (22-55 lbs) used EpiPen Jr – 0.15 mg per dose (anterolateral aspect of the middle third of the thigh)***
  • MOA: bronchial smooth muscle relaxation, vasoconstriction Repeat Q 5-15 mins if symptoms persist
  • ***Overweight or obese children, administration into the lower half or into the calf --greater chance of intramuscular administration


Know How to Use EpiPen


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What about Auvi-Q?


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Parent Education: Take steps to avoid reactions!

  • ◦Ask about ingredients
  • ◦Washing your hands and your child’s hands before handling food
  • ◦Educate family, friends, and others
  • ◦Teach your child how to manage his or her food allergies
  • ◦Focus on what safe foods your child can have, rather than what he or she can’t have
  • ◦Make sure child is getting adequate nutrition


Parent Action Plan: Be Prepared…Be Safe

•An effective food allergy treatment plan
•Strict avoidance of problem foods
•Working with your doctor to develop a Food Allergy & Anaphylaxis Emergency Care Plan
•Emergency medical ID
•Carrying medication 24/7: Always have 2 EpiPens!
•Medication at the first sign of a reaction
•Getting to an emergency room for follow-up treatment if experiencing  severe reaction



Allergies at School: how many and who is at highest risk

  • •16-18% of children with food allergies have a reaction in school
  • •25% of anaphylactic reactions occurred in children not yet diagnosed with food allergies
  • •Teenagers are at highest risk of food induced anaphylaxis


Food allergies: Management in Schools


Common Accommodations at school for food allergies

  • •Classroom
  • •Recess and PE
  • •Cafeteria
  • •After school programs and field trips
  • •Transportation
  • *Have rapid access to epinephrine & trained staff


Egg Allergy & Immunizations: AAP Redbook 2015

What is an egg allergy and considerations for specific immunizations

  • • IgE response to egg protein
  • • Affects 1 to 2 percent of young children
  • • What is safe to give:
    • •MMR, varicella
    • •Influenza--exceptions (see algorithm)
  • • Contact allergist:
    • •Yellow fever
    • •Rabies
    • •If necessary perform allergy eval & vaccine testing FIRST


Recommendations regarding influenza vaccination of persons who report allergy to eggs*† — Advisory Committee on Immunization Practices, United States, 2015–16 influenza season

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