Food allergy - assessment and management Flashcards
define allergy
not key just broad idea
“immunological hypersensitivity that can lead to a variety of different diseases via different pathomechanisms with different approaches in diagnosis, therapy and
prevention”.
just some key terms to have a read of…
Allergen - Any substance stimulating the production of IgE or a cellular immune response. Usually a protein, but can be carbohydrates (much less common)
Sensitivity - Normal response to a stimulus
Hypersensitivity - Abnormally strong response to a stimulus.
Sensitisation Production of IgE antibodies after repeated exposure to an allergen.
A hypersensitivity reaction initiated by specific immunological mechanisms. This can be IgE mediated (e.g. peanut allergy) or non-IgE mediated (e.g. milk allergy).
Atopy - A tendency to produce IgE antibodies in response to ordinary exposure to potential allergens. Strongly associated with asthma, rhinitis, eczema and food allergy.
Anaphylaxis A serious allergic reaction with bronchial, laryngeal and cardiovascular involvement that is rapid in onset and can cause death.
Food allergy - Immunologically mediated adverse reaction to food.
outline some key facts about milk allergy
- Commonest food allergy in infants – affects 2-3%.
- Always presents by 12 months of age.
- Symptoms can present many weeks after first ingested.
- Two types of presentation:
- Immediate-onset IgE mediated (40%)
- Typical allergy symptoms affecting skin, respiratory and GI tracts.
- Symptoms of urticaria, cough, wheeze, vomiting and diarrhoea.
- Can cause anaphylaxis and even be fatal.
- Delayed-onset non-IgE mediated (60%)
- Predominantly multiple GI symptoms.
- Difficult to diagnose: younger presentation similar to colic, reflux.
how may an IgE mediated and a non IgE mediated food allergy present
key info is that there are these two types of true food allergy
Feature IgE mediated Non IgE-mediated
Symptom onset
• Immediate – 5-30 min • Delayed – hours to days
Common foods
• Milk and eggs • Milk and soya wheat, rice
• Peanuts and tree nuts
• Fish and shellfish
• Fruit and vegetables (PFS)
Presenting age
Variable – age of contact • Infancy & early childhood
• All milk allergy by 1 year
• All milk allergy by 1 year
Natural history
Resolve earlier than IgE • Many by school age
• Milk and egg allergy can
resolve; others persistent
into adulthood
Different presentations of immediate-onset food allergy
read
Pollen food syndrome
Pruritus and mild oedema confined to the oral cavity (lips, tongue, mouth and throat) uncommonly progressing. Associated with hay fever (raw fruit and vegetables)
Food-associated exercise induced anaphylaxis
Food triggers anaphylaxis only if ingestion is followed
temporally (within 2 hours) by exercise. (wheat, shellfish, celery)
Anaphylaxis Rapidly progressive, potentially fatal, multiple organ system reaction with respiratory symptoms and can include cardiovascular. (nuts, fish, shellfish, milk, eggs)
Urticaria/ Angioedema Acute (rarely chronic) hives and swelling with gastrointestinal but not respiratory or CVS symptoms. (any)
Different presentations of delayed-onset food allergy
read
Proctocolitis Passage of bright red blood in mucousy stools in otherwise asymptomatic infants. (milk, through breast feeding)
Enterocolitis Multiple and varying gastrointestinal symptoms including feed refusal, persistent vomiting, abdominal cramps, loose and frequent stools and constipation. (milk, eggs, wheat)
Eosinophilic oesophagitis Symptoms from oesophageal inflammation and scarring of feeding disorders, reflux symptoms, vomiting, dysphagia and food impaction. (milk, eggs, wheat)
Food proteininduced enterocolitis syndrome
Primarily affects infants. Profuse vomiting leading to
pallor, lethargy and possibly shock; diarrhoea in 25%.
(milk, soya, rice, wheat, meat)
bonus
cooking some foods will allow allergic people to eat them by destroying protien/carb complex
ie wheat, lactose, apple
what is a skin prick test
dabbing many allergens onto skin
seeing what blows up
how can we diagnose a food allergy
Using sIgE screening tests in immediate onset symptoms
Detect IgE:
• Serum specific IgE – IgE circulating in blood
• Skin prick tests – Response of skin mast cells to allergens
• Determine presence of sensitivity not allergy
• Level of sIgE / size of SPT correlates with likelihood of allergy
Targeting likely allergens
outline the managment of a food allergy
- Appropriate assessment
- Allergy focused history and examination.
- Appropriately selected allergy investigations.
- Identify food causing symptoms.
• Dietary advice
• Exclusions – which food/food groups/food formats to avoid.
• Inclusion – which food/groups/formats not to avoid.
• Label reading: Ingredient labeling.
Food reintroductions.
- Medical advice
- Emergency management of allergic/anaphylactic reaction.
these are the classic non ige mediatied food allergy symptoms
these are the classic non ige meidatied food allergy symptoms
Gastrointestinal system Food refusal or aversion - feeds slwoly, fussy Abdominal pain; infantile colic Gastro-oesophageal reflux disease* - vomits after feeds Loose or frequent stools Blood and/or mucus in stools Constipation* - cries when passing stool Perianal redness Pallor and tiredness Faltering growth
read - what is lactose intolerance
Lactase evolution and action • Detection from 8 weeks gestation; rise from 32 weeks to peak at birth. • Activity decreases within months. • Present on jejunal brush border apex. • Hydrolysis of lactose into monosaccharides galactose and glucose
Lactose intolerance (Lactase non-persistence)
• Occurs in most humans; variable.
• Typical symptoms: bloating, flatulence,
explosive diarrhoea.
• Onset subtle; progressive over years.
• Most diagnosed as adolescent or adult.
• Not always symptomatic with milk.
how would we manage a milk allergy
stepwise milk ladder reintroduction
biscuit crumb - half busicit ——-ect——pint of milk like a champ
classic symptoms of IgE mediated anaphylaxsis
Symptoms • Well child; mild eczema. • Acute onset of symptoms. • Coughing; scratching throat. • Red face. • Repeated vomiting. • Generalised urticaria. • No breathing problems.
Skin
Pruritus, erythema
Acute urticaria – localised or generalised
Acute angioedema – most commonly of lips, face and around eyes
Gastrointestinal system
Angioedema of lips, tongue and palate
Oral pruritus; nausea, vomiting, diarrhoea
Colicky abdominal pain
Respiratory system (usually with above)
Upper resp -blocked/runny nose, sneeze, itch
Lower resp - wheeze, cough, DIB
Cardiovascular system (rarely in food allergy)
Pallor, drowsy, hypotensive
dietary / label advice
on food packs we put major allergens in bold
also make sure patient carries an epipen and knows how to correctly use it
