1. ALLERGY IN GENERAL PRACTICE
Dr Jeanne Powell

2. THE ESSENTIAL GP TOOL KIT
“I think I must be allergic to something, Doctor”
THE ESSENTIAL GP TOOL KIT

3. Gell and Coombs Classification
TYPE I IgE mediated
Allergy to protein
TYPE II IgG response
Cell lysis
TYPE III IgG or IgM mediated
Immune complex deposition
TYPE IV T cell mediated
Delayed hypersensitivity

6. Interrelationships between Allergy and Hyperresponsiveness
IgE sensitisation
Non-IgE hyperresponsiveness
IgE allergic
hyperresponsiveness
‘Latent’ allergy clinical tolerance
Asthma
Rhinitis/Conjunctivitis
Food/drug reaction
Urticaria/angioedema
Anaphylaxis

7. Grading system for Anaphylaxis
GRADE
Brown et al 2006 1
MILD
Skin and subcutaneous tissues only:
Generalised erythema, urticaria, periorbital oedema or angioedema 2
MODERATE
Respiratory, cardiovascular or gastrointestinal involvement:
Dyspnoea, stridor, hoarseness, wheeze
Nausea, vomiting
Dizziness (presyncope), diaphoresis
Chest or throat tightness, abdominal pain 3
SEVERE
Hypoxia, hypotension or neurological compromise: Cyanosis or SpO2≤92%
Systolic blood pressure<90mmHg in adults
Confusion, collapse, loss of consciousness

8. Management of Anaphylaxis
RESCUE KIT:
MILD: Anti-histamine high dose
MODERATE: ADD Soluble prednisolone 30mg (0.5mg/kg)
SEVERE: ADD Adrenaline auto injector
300mcg over 30kg
150mcg 15-30kg

9. PRACTICAL ALLERGY

10. Allergy in 10 minutes DETECTIVE WORK
Presenting episode vs Previous episodes
Consistent trigger (<4 hours) or pattern to episodes
Co-factors - exercise/alcohol/NSAIDS/intercurrent illness
Dose of allergen vs severity of reaction
Atopic medical history - CONCURRENT ASTHMA

12. Case Study 35 year old secretary
Itchy rash – moves about over torso and limbs
Increasing in frequency/severity for 4 weeks
Has been to A&E twice with facial swelling
Treated with steroids - briefly successful
Taking OTC cetirizine PRN, then daily
Had an infected insect bite about a month ago
Wants to find out what to what she is allergic

13. Urticaria in 10 minutes Lesions itchy NOT painful/bruising
Pattern/duration
Consistent link with particular trigger
Foods: usually present within 4 hours
Relationship to temperature/pressure/exercise
Associated swelling/systemic symptoms
Associated asthma / atopy / AI disease
Family history (HAE/thyroid/AI)

14. Examination Presence of: Examine lesions if present Thyromegaly?
Dermographism?
Examine lesions if present

15. Urticaria with/without Angioedema
Idiopathic MAJORITY
Physical Dermographism
Stress, Viral infections
Cholinergic
Cold/aquagenic/solar/vibratory
Delayed Pressure Urticaria
Allergic Food, Venom, Latex, Contact urticaria
Drug Induced Opiates, NSAIDs, Antibiotics, Statins,
Anti-depressants
Urticarial Vasculitis Infection
Drugs : penicillin, allopurinol, quinolones, carbemazepine
Autoimmune, paraproteinaemia, malignancy

16. Investigations May not need any!
If dermographic- SPT may not be helpful
Consider TFT, TPO, ANA, C3 and C4

17. Have the explanatory chat
This really does save time in the long run!

18. Treatment BEGIN REGULAR: Fexofenadine 180mg up to bd
ADD Ranitidine 150mg bd
ADD Montelukast 10mg nocte
RESCUE:
Chlorpheniramine 8mg nocte or
Cetirizine/Loratadine 10mg bd PRN

19. Case Study 55 year old pilot, 10 year history of:
1 or 2 episodes/month of variable severity of hives/lip swelling- settles with fexofenadine
5 bad episodes of severe urticaria, swelling and fainting, most whilst away in Wales
Routinely goes to the gym on most mornings
No foods avoided
Takes fexofenadine before flights to prevent episodes

20. Wheat Dependent Exercise Induced Anaphylaxis
Anaphylaxis dependent on combination of wheat dose and exercise within a 4 hour period
Symptoms vary from urticaria through to severe anaphylaxis
Positive Omega-5-Gliadin (Tri a 19)
Positive SPT to wheat hydrolysate
May have negative test to wheat and gluten
Referral important – dietician/assessment
Prophylactic antihistamines

21. Case Study 72 year old retired accountant
Hypertension for 6 years - on ramipril & statin
MI 1 year ago - on bisoprolol & aspirin since
Monthly facial swellings began 8 months ago
In the last month- 2 episodes of tongue swelling overnight- Called ambulance
Rx prednisolone/AH and taken to A&E for obs.
Now carries adrenaline

23. Isolated Angioedema
Idiopathic Majority Drugs Oestrogen, ARB, NSAID, Antibiotics, Statins ACE-Inhibitors Not necessarily recently started Allergic Food, Venom, Latex Physical Delayed Pressure Hereditary Angioedema usually presents before age 20 Acquired C1 esterase deficiency especially older age groups

24. Investigations IgE, SpIgE / Phadiotop – from history! TFT/TPO /HR Ab*
Isolated Angiodema:
C3, C4, C1 inhibitor
Immunoglobulins
Electrophoresis

25. Treatment REGULAR DAILY Anti-histamine- high dose H1 antagonist
Cetirizine 10mg bd
OR Fexofenadine up to 180mg bd
Add H2 receptor antagonist
Ranitidine 150mg bd
Add Leukotriene antagonist
Montelukast 10mg nocte
Add other drugs
Second anti-histamine (Tranexamic acid, steroids, azathioprine)

26. Rescue Mild swelling (outside teeth) Moderate swelling (inside mouth)
Piriton 8mg/cetirizine 10-20mg
Moderate swelling (inside mouth)
ADD Soluble prednisolone 30mg
Severe swelling (affecting throat)
ADD Adrenaline auto injector

27. Case Study 16 year old boy, GCSE year
Hay fever from late spring to summer
Itchy eyes, sneezing and stuffy nose
Blocked ears and itchy palate
Takes OTC anti-histamines PRN
Wants to know if there is a cure as fed up!

28. Hay fever Spring: Tree pollen (January to May)
Summer: Grass pollen (June)
Autumn: Weed pollen (September)
Perennial: Animal dander
Mould spores
House Dust Mite

29. Investigations
No testing really needed unless considering referral for Sub Lingual Immunotherapy (SLIT)
Skin prick testing ideal
Sp IgE also useful
Phadiotop : house dust mite, grass and tree pollen, cat dander

30. Treatment: Hay fever Start daily 2/52 prior to earliest symptoms
‘Itchy –Sneezies’: Antihistamines up to bd
Nasal congestion: Intranasal Steroids up to bd
Fluticasone nasules 6 drops each nostril bd for 2 weeks
INS spray bd, reducing to daily when possible
Eyes: Na cromoglycate
ADD Montelukast 10mg nocte
ADD Rescue steroids 5 days
REFER SLIT (season on maximal Rx

31. Case Study 31 year old teacher
Itchy mouth and lips after eating apple, peach, cherry, raw carrot and hazelnuts
Apple pie and tinned peaches - no symptoms
Peeling potatoes- itchy eyes and sneezing
Hay fever in May
Mild asthma and eczema

32. Oral Allergy Syndrome Food cross reactions to Silver Birch pollen
Associated hay fever in May
Heat labile proteins primarily limited to pulp of fruit
Cooked and processed foods often tolerated
Common fruit & vegetable allergy in Northern Europe

33. Examples of cross reacting foods: Birch Pollen
ROSE FAMILY:
Carrot
Apple
Potato
Pear
Hazelnut
Parsnip
Cherry
Brazil nut
Onion
Peach
Almond
Tomato
Nectarine
Peanut
Celery
Plum
Walnut
Spinach
Honey
Fennel

34. Grass Pollen Melon Patients need only avoid foods causing symptoms
Orange
Tomato
(not all cross reacting foods)
Watermelon
Wheat
Swiss chard

35. Severe OAS (LTP Allergy)
Proteins stable to heat and digestion
Primarily in peel of fruit or vegetable
Reactions also to cooked and processed foods
Often associated with severe and systemic reactions as well as OAS
Commonly related to allergic reactions to fruit and vegetables in Southern Europe

36. Summary: Severe vs Mild OAS vs Latex
Myriad of possible cross reactions are possible and so can be very difficult to discern
Overall, I look for a pattern
Consider:
Extent of food cross reactions
Raw vs Cooked reactions
Severity of reactions
Associated allergens - pollens/latex
Co-existing asthma

37. Skin Prick Testing Safe for airborne allergens
Small risk of anaphylaxis for other tests
Rapid result and highly acceptable test
Not freely available in GP

38. Specific IgE Testing
Looks for antibodies to specific allergenic protein extract so a safe test
Grade 0 (negative) to Grade 6 (positive)
BUT:
Sp IgE Sensitisation Clinical allergy
Strength of positive Clinical severity
False positives: Cross reacting proteins
Very high IgE levels (eczema)

39. Component Resolved Diagnosis
Allergenic Food Source
Skin prick tests
Allergenic Extract
Specific IgE
Unique allergen molecules
Cross-reactive allergen molecules
Component Resolved Diagnostics

40. CRD Testing for Nut Allergy
Request Ara h2 and Ara h8
If Ara h8 positive = Oral Allergy Syndrome and lower risk of severe systemic reaction
If Ara h2 positive = True Nut Allergy likely and higher risk of severe systemic reaction
AVOIDANCE IS STILL NEEDED
Affected by allergen load and patient factors

41. Case Study: 6 year old boy, new to area
Peanut butter at 2 years - facial swelling, hives and vomiting
SPT positive to peanut, and brazil nut 2 years ago
Successfully avoided nuts since, carries piriton
Eczema as a baby, now has mild asthma
Referred to check if still allergic to nuts
Younger sibling aged 2 has never had nuts

42. Investigating Nut allergy
Skin prick tests
Quick result, small risk anaphylaxis
>8mm - assumed allergic
SpIgE:
Nut mix 1 (peanut, hazelnut, brazil, almond, coconut)
Nut mix 2 (Cashew, pecan, pistacio, walnut)
False positives and negatives
Severity can’t be inferred from results

43. Nut Allergy Spectrum of disease 1 in 3 children may outgrow allergy
This more likely if allergy before age of 2 years
BUT some of these children redevelop allergy
Therefore regarded as an enduring allergy
Sibling risk 1:10 (Graduated skin challenge)
Peanut densensitisation subject of trials only

44. Case Study 28 year old motorbike salesman for Europe
Stung mid chest whilst out on motorbike
Within minutes- metallic taste in mouth, chest pain and DIB- pulled into service station
Collapsed - passing doctor treated him with adrenaline/steroids (!!)
Previous stings: 8 years before and 2 months previously– Large local reaction only

45. Venom Allergy Hymenoptera : bee, wasp, hornet
High risk occupations/hobbies
Causes 20% of fatal anaphylaxis cases in UK
Refer systemic reactions for consideration of VIT
Bloods: Sp IgE bee/wasp venom and Serum tryptase

46. Venom Allergy Large Local Reactions: Systemic Reactions:
Any swelling contiguous with sting
Treat with prednisolone
Systemic Reactions:
Any symptoms occurring apart from sting
Adrenaline carriage mandatory
Venom immunotherapy ~3 years (95-98% success)

47. When to Refer Symptoms do not respond to treatment/avoidance
Confirmed IgE mediated food allergy with asthma
Tests are negative but a strong suspicion of allergy
Anaphylaxis of uncertain cause
Review of condition/for retesting/management
Concern (doctor and/or patient!)

48. Useful Websites Advice leaflets: Anaphylaxis : Guidelines:
Anaphylaxis :
Guidelines:
BSACI/EAACI*

49. Thank you
Any questions?