diagnosing food allergy - cyans...diagnosing food allergy advances, pitfalls and problems rosie...
TRANSCRIPT
![Page 1: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/1.jpg)
Diagnosing food allergy Advances, pitfalls and problems
Rosie Hague
Consultant in Paediatric Allergy, Immunology and Infectious Diseases
RHSC Yorkhill
![Page 2: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/2.jpg)
Conditions attributed to food allergy
l Anaphylaxis l Urticaria l Eczema l Gastro-oesophageal
reflux l Vomiting l Colic l Diarrhoea l Constipation
l Abdominal pain l Irritable bowel l Depression l Autism l Glue ear (catarrh) l Chronic fatigue l Hyperactivity
![Page 3: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/3.jpg)
Pitfall number 1
Taking the label of “allergy” at face value
![Page 4: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/4.jpg)
Types of adverse reaction to foods
l IgE mediated immune reactions l Non-IgE mediated immune reactions l Non-allergic food intolerance
l Pharmacological l Metabolic l Toxic
l Food aversion
![Page 5: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/5.jpg)
A careful history is the best tool in the diagnosis of allergy
![Page 6: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/6.jpg)
The history
l Nature and duration of symptoms l Possible precipitants, and timescale l Previous exposure to possible precipitant l Previous reactions l Tolerance of/exposure to related allergens l What foods avoiding and why
![Page 7: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/7.jpg)
History of atopy
l Asthma l Eczema l Hay fever l Contact dermatitis l Drug reactions
l Family history
![Page 8: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/8.jpg)
Symptoms associated with IgE mediated allergic reactions
l Rash l Itch l Sneezing l Swollen lips l Metallic taste in mouth
l Hoarse voice l Lump in the throat l Wheezing l Nausea and vomiting l Abdominal cramps
![Page 9: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/9.jpg)
Symptoms associated with IgE mediated allergic reactions
l Rash l Itch l Sneezing l Swollen lips l Metallic taste in mouth
l Hoarse voice l Lump in the throat l Wheezing l Nausea and vomiting l Abdominal cramps
![Page 10: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/10.jpg)
Anaphylaxis?
l Urticaria l Angioedema l Acute wheeze l Acute stridor l Shock
![Page 11: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/11.jpg)
Non IgE mediated allergy
l Itch l Erythema l Atopic eczema
l Pallor and tiredness l Growth faltering with 1
or more GI symptoms
l GO reflux disease l Loose/frequent stools l Blood/mucous in stools l Abdominal pain/colic l Food refusal/aversion l Constipation l Peri-anal redness
![Page 12: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/12.jpg)
These are probably not allergy
l Urticaria with no obvious precipitant l Peri-oral/contact erythema l Isolated behavioural disturbance l Chronic GI symptoms unresponsive to dietary
manipulation
![Page 13: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/13.jpg)
Acute Urticaria < 6 weeks duration
Detailed history may identify trigger e.g drug reaction, viral illness (urticaria days
to weeks) or food allergy (urticaria hours)
Chronic Urticaria > 6 weeks duration Regular episodes. May have associated urticaria in response to physical stimuli (dermographism, pressure, cold, heat)
Allergen not identified
Refer to Consultant Dermatologist if:
• Persistent> 3 months • Unresponsive to 3 different
antihistamines each for 4-6 weeks • Additional symptoms or bruising
Test rarely required unless evidence of systemic disease or history of additional symptoms or signs such as bruising (suggesting urticarial vasculitis)
or joint swelling
|Usually autoimmune. Occasionally occurs in association with underlying infection or as part of autoinflammatory syndrome
(when presenting in early childhood with associated pyrexia, malaise and joint or abdominal pain)
May be associated with other autoimmune conditions such as thyroid disease.
Management: Chlorpheniramine if < 6 months
Long acting antihistamine if > 6 months e.g fexofenadine, cetirizine, loratadine Sedative anti-histamine at night if sleep
disturbed
Allergen identified: Give interim avoidance advice, an allergy management plan (including chlorpheniramine)
and refer to allergy clinic
![Page 14: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/14.jpg)
![Page 15: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/15.jpg)
Pitfall number 2
Testing before engaging brain!
![Page 16: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/16.jpg)
If the clinical picture is not of IgE mediated disease, don’t do
IgE based tests!
![Page 17: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/17.jpg)
Trial of elimination
l Eliminate suspected food for 2-6 weeks
l Symptom diary before during and after
l Re-introduce after trial
![Page 18: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/18.jpg)
IgE based tests
![Page 19: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/19.jpg)
Pitfall number 3
Asking the wrong question of the test
![Page 20: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/20.jpg)
Rosie’s laws
l Never do a test if you don’t want the results! l Don’t do a test without a supportive history l Don’t do a test which won’t alter management
![Page 21: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/21.jpg)
Skin prick testing
l Rapid l Cheap l Result on the day l Correlate well with type I symptoms
![Page 22: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/22.jpg)
Problems of skin prick testing
l Less useful in <1year l Antihistamine use l Not possible in severe eczema l Hard to interpret small wheals l Occasional anaphylaxis
![Page 23: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/23.jpg)
Serological tests (ImmunoCap)
l measures specific IgE l safe l not influenced by antihistamine l high values correlate reasonably
well with risk of type 1 reactions
![Page 24: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/24.jpg)
Problems of specific IgE tests
l Very accessible l “food mix” l Too tempting to ask for lots! l Difficult to intepret in children with very high
total IgE l Titre does not correlate with severity of reaction l Testing without history l Cost
![Page 25: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/25.jpg)
Oral provocation test
l “Gold standard” l Cannula if previous
severe acute reaction l Apply to skin l Apply to lips l Ingest increasing
amounts
![Page 26: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/26.jpg)
Problems in oral challenge
l Use of open method when symptoms subjective l Insufficient observation to detect delayed
reactions l Inappropriate formulation of test food l False negative in food related exercise induced
anaphylaxis l Labour/resource intensive
![Page 27: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/27.jpg)
Are there any advances?
Component testing
![Page 28: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/28.jpg)
Allergenic components of peanuts
Component Protein tye comments
Ara H 1 Storage protein Peanut specific marker
Ara H2 Storage protein Peanut specific marker
Ara H3 Storage protein Peanut specific marker
Ara H5 Profilin Marker of grass pollen cross reactivity
Ara H6 Storage protein Similar to ara H2
Ara H8 PR10 protein Marker of birch pollen cross reactivity
Ara H9 Ns LTP Marker of peach cross reactivity
![Page 29: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/29.jpg)
What about eggs?
l Ovomucoid l Heat stable
l Ovalbumin l Conalbumin l Lysozyme
![Page 30: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/30.jpg)
What you get
![Page 31: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/31.jpg)
The problem of idiopathic anaphylaxis
l History still essential l Don’t forget exercise
induced! l 20% diagnosis
assisted with ISAC l wheat l nut l lupin
![Page 32: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/32.jpg)
Pitfall number 4
Getting an answer to a question you never asked!
![Page 33: Diagnosing food allergy - CYANS...Diagnosing food allergy Advances, pitfalls and problems Rosie Hague Consultant in Paediatric Allergy, Immunology and Infectious Diseases RHSC YorkhillTypes](https://reader034.vdocuments.mx/reader034/viewer/2022042309/5ed5dc779d478371bd77727a/html5/thumbnails/33.jpg)
Take home message
l Make a clinical diagnosis first! l Decide what the question is before deciding on
the test l Pick the right test and know how to interprete
it. l Never do a test which will not influence
management l Never do a test if you don’t want the result!