ALLERGY IN GENERAL PRACTICE Dr Jeanne Powell

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

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

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

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

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

PRACTICAL ALLERGY

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

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

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)

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

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

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

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

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

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

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

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

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

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

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)

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

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!

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

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

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

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

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

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

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

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

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

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

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)

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

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

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

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

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

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

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

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)

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!)

Useful Websites Advice leaflets: Anaphylaxis : Guidelines: www.patient.co.uk Anaphylaxis : www.anaphylaxis.org www.yellowcross.co.uk www.jext.co.uk Guidelines: BSACI/EAACI*

Thank you Any questions?