ALLERGY IN GENERAL PRACTICE

Dr Jeanne Powell

“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 TYPE IV IgG or IgM mediated Immune complex deposition T cell mediated Delayed hypersensitivity

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

GRADE 1 MILD 2 MODERATE 3 SEVERE Grading system for Anaphylaxis

Brown et al 2006 Skin and subcutaneous tissues only:

Generalised erythema, urticaria, periorbital oedema or angioedema

Respiratory, cardiovascular or gastrointestinal involvement:

Dyspnoea, stridor, hoarseness, wheeze Nausea, vomiting Dizziness (presyncope), diaphoresis Chest or throat tightness, abdominal pain

Hypoxia, hypotension or neurological compromise:

Cyanosis or SpO 2 ≤92% Systolic blood pressure<90mmHg in adults Confusion, collapse, loss of consciousness

Management of Anaphylaxis RESCUE KIT:

MILD: Anti-histamine high dose MODERATE: SEVERE: ADD Soluble prednisolone 30mg (0.5mg/kg) ADD Adrenaline auto injector 300mcg over 30kg 150mcg 15-30kg

PRACTICAL ALLERGY

Allergy in 10 minutes

DETECTIVE WORK

• Presenting episode vs Previous episodes •

Consistent

episodes trigger (<4 hours) or pattern to • Co-factors - exercise/alcohol/NSAIDS/intercurrent illness • Dose of allergen vs severity of reaction • Atopic medical history - CONCURRENT ASTHMA

Top 8 Food allergens

Peanuts Fish Treenuts Eggs Dairy Shellfish Soy Wheat

• • • • • • • •

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: – Thyromegaly?

– Dermographism?

Examine lesions if present

Urticaria with/without Angioedema

Idiopathic Physical Allergic Drug Induced Urticarial Vasculitis MAJORITY Dermographism Stress, Viral infections Cholinergic Cold/aquagenic/solar/vibratory Delayed Pressure Urticaria Food, Venom, Latex, Contact urticaria Opiates, NSAIDs, Antibiotics, Statins, Anti-depressants 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

49%

Isolated Angioedema

24% 3% 1% 2% 13% 8% ACE-I related angioedema Other drug related angioedema Allergic angioedema Physical angioedema Hereditary angioedema Acquired angioedema Idiopathic angioedema 384 patients RSCH 2003-09

Isolated Angioedema

Idiopathic Drugs Majority Oestrogen, ARB, NSAID, Antibiotics, Statins ACE-Inhibitors Not necessarily recently started Allergic Physical Food, Venom, Latex 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) – 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: • Summer: • Autumn: • Perennial: Tree pollen (January to May) Grass pollen (June) Weed pollen (September) 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: ADD ADD REFER Na cromoglycate Montelukast 10mg nocte Rescue steroids 5 days 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: Apple Pear Cherry Peach Nectarine Plum Honey • • • • • Hazelnut Brazil nut Almond Peanut Walnut • • • • • • • • Carrot Potato Parsnip Onion Tomato Celery Spinach Fennel

Grass Pollen

• • • • • • Melon Orange Tomato Watermelon Wheat Swiss chard

Patients need only avoid foods causing symptoms (not all cross reacting foods)

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 Strength of positive Clinical allergy 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: – 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: • www.patient.co.uk

• Anaphylaxis : • www.anaphylaxis.org

• • www.yellowcross.co.uk

www.jext.co.uk

• Guidelines: • BSACI/EAACI*

Thank you Any questions?