Food Allergy Flashcards

1
Q

Define food allergy

A

Adverse health effect arising from a specific immune response that occurs on exposure to food

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2
Q

Types of food allergies

A
  • IgE-mediated
  • non IgE-mediated
  • mixed
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3
Q

Examples of IgE mediated food allergy

A
  • anaphylaxis
  • urticaria
  • angioedema
  • acute asthma
  • acute rhinitis
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4
Q

Examples of non-IgE mediated food allergy

A
  • contact dermatitis
  • celiac disease
  • dermatitis herpetiformis
  • FPIES
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5
Q

What is a food intolerance

A

Adverse response to food that does not involve the immune response

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6
Q

What are the commonest IgE mediated food allergies?

A

Milk
Egg
Peanuts

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7
Q

Compare the prevalence of self reported allergies vs challenge proven allergy

A

Self reported can be 6x higher than challenge proven

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8
Q

Types of food intolerances

A

Food characteristics
Host characteristics

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9
Q

Describe food intolerances due to food characteristics

A
  • reaction that results from eating spoiled food
    -e.g. spoiled oily fish where exces histamines produced from decay produce similar allergysymptoms
  • reaction to pharmacologically active food components
    -e.g. caffeine
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10
Q

Describe food intolerances due to host characteristics

A
  • metabolic disorders e.g. lactose intolerance
  • psychological or neurological response e.g. food aversion + rhinorrhoea due to spicy food
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11
Q

What are the 2 commonest non IgE mediated food allergies?

A

Milk
Soya

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12
Q

Compare the symptom onset of IgE + non IgE mediated food allergies

A
  • IgE: immediate 5-30 mins
  • non IgE: delayed hours -days
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13
Q

Compare the systems affected by IgE + non IgE mediated food allergy

A
  • IgE: skin, GI tract, resp system, CVS
  • non IgE: GI tract, eczema?
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14
Q

IgE mediated food allergy symptoms

A
  • erythema
  • angioedma
  • urticaria
  • N + V, diarrhoea
  • dyspnoea + cough
  • pallor
  • hypotension
  • colicky abdo pain
  • behavioural changes (anxiety, agitation)
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15
Q

Non IgE mediated food allergy symptoms

A
  • vague
  • often GI symptoms > can mimic GI conditions
  • delayed presentation
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16
Q

What is protocolitis?
Common food trigger
IgE or non-IgE?

A
  • Passage of bright red blood in mucously stool in otherwise asymptomatic infant
  • milk
  • non IgE
17
Q

What is pollen food syndrome?
Common food triggers
IgE or non IgE?

A
  • Pruritus + mild oedema of oral cavity
  • assocaited with hay fever | uncooked fruit, veg + nuts
  • IgE
18
Q

What is food associated exercise induced anaphylaxis?
Common food triggers
IgE or non IgE?

A
  • food triggers anaphylaxis only if ingestion is followed by exercise within 2 hours
  • wheat, shellfish, celery
  • IgE
19
Q

What is enterocolitis?
Common food trigger
IgE or non-IgE?

A
  • multiple + varying GI symptoms including feed refusal, persistent vomiting, abdominal cramps, loose + frequent stools + constipation
  • milk, eggs, wheat
  • non IgE
20
Q

What is FPIES?
Common food trigger
IgE or non-IgE?

A
  • food protein induced enterocolitis syndrome
  • in infants with symptoms of profuse vomiting leading to pallor, lethargy + shock
  • milk, soya, rice, wheat, meat
  • non IgE
21
Q

What is the commonest food allergy in adults?

A

Pollen food syndrome

22
Q

Diagnosis of food allergies

A
  • history
  • presenting symptoms
  • details about food ingested
  • physical exam
  • screening tests
  • diagnosis verification with oral food challenges
23
Q

Behavioural changes in IgE mediated food allergy

A
  • quiet
  • anxiety
  • agitation
  • sense of impending doom
24
Q

Investigations of food allergies

A
  • Skin prick test
  • Specific IgE blood test
  • Challenge:
    -open food challenge
    -single blinded challenge
    -double blinded placebo control food challenge
25
Q

Skin prick test vs specific IgE blood test

A
  • SPT: reflects IgE bound to cutaneous mast cells + subsequent release of mediators like histamines
  • sIgE: reflects sIgE within the blood
26
Q

Outline sIgE blood test

A
  • allergen absorbed + immobilised to solid phase
  • patient’s serum is added followed by incubation for 30-60 mins
  • washing steps
  • allergy bound IgE detected by enzymatically labelled anti human IgE monoclonal antibody
27
Q

Outline skin prick test

A
  • sterile needed used to add suspected allergen to skin
  • positive if skin becomes red and swollen
28
Q

Food allergy management

A
  • medical management plan
  • dietitian management
  • consider co-morbidities e.g. asthma, hayfever, eczema
29
Q

What would a history of acute reaction with clear identifiable trigger + positive test suggest?

A

Allergy

30
Q

What would no history of exposure + positive test suggest?

A

Sensitisation

31
Q

What would a history of eating food + positive test suggest?

A

Sensitisation but tolerant

32
Q

What should you do if:
- positive SpIgE + no reaction to food
- negative SpIgE + reaction history

A

Believe the history

33
Q

Explain how you would test a food allergy by exclusion

A

Complete exclusion for 4 weeks followed by reintroduction

34
Q

What food commonly cause FPIES

A

Milk
Soya
Fish
Eggs
Rce

35
Q

Treatment of eczema

A

250-500g emollient per week

36
Q

What is sensitisation?

A

Production of IgE antibodies after repeated exposure to an allergen

37
Q

explain the difference between FPIES and cows milk allergy

A
  • FPIES: non IgE mediated food allergy > complex immune system activation without dominant role of IgE | symptoms occur several hours after ingestion + mainly in GI tract
  • cow’s milk allergy: IgE mediated food allergy > mast cell degranulation |symptoms are immediate