Offshoot Newsletter May
IgE mediated food allergy is increasing in Australia. 1 in 10 children at 12 months of age in Australia has a clinical proven food allergy, with egg, cow milk and peanut being among the three most common IgE mediated food allergies. Often young children with food allergy have eczema, and the combination of food allergies and eczema can have a significant impact on the quality of life of parents and their allergic child. Proper diagnosis and management and understanding of the limitations of food allergy testing is paramount.
When should we suspect an IgE-mediated food allergy?
Severe eczema, particularly in infancy, increases the risk of IgE mediated food allergy. IgE mediated food allergy should be suspected in any children when there is an immediate reaction (usually within 1-2 hours of ingestion) following ingestion of a food, resulting in symptoms/signs involving the cutaneous (urticaria, hives, angioedema, eczema flares), gastrointestinal (vomiting, abdominal pain), respiratory (wheeze, cough, difficulty breathing, hoarse voice), and/or cardiovascular systems (floppy, hypotension).
How we confirm IgE mediated food allergies
Either by skin prick testing (SPT) or ssIgE (formerly called RAST testing). Both are testing sensitization (i.e development of IgE antibodies to a food allergen). SPT is easy to perform the results are quickly available and many different allergens can be ordered. ssIgE does involve a blood test, and currently only 4 allergens are currently covered by Medicare.
Panel testing should not be done, and instead specific food allergens should be ordered based on the clinical history. For example, if a child has immediately developed urticaria after drinking cow milk, then SPT/ssIgE to cow milk and soy should be done (as soy is usually the safest alternative). The interpretation of the SPT/ssIgE can sometimes be complex, but some general rules are:
- The larger the test size the more likely the child will react; a negative test usually means the child is likely to tolerate that food.
- The test size can not predict the severity of any future reaction (i.e 20 mm peanut SPT does not mean the child is at more risk of anaphylaxis compared to a child with a 10 mm peanut SPT)
- Never perform a SPT/ssIgE to a food a child is tolerating in the diet without immediate reaction, as false positive reactions are not uncommon, leading to unnecessary avoidance in the child’s diet.
Management of IgE mediated food allergies
Currently management of IgE mediated food allergies involves avoiding the trigger(s) in question, determining if a modified version of the food protein can be ingested under medical observation (e.g. in those with egg/cow milk allergy, often we can perform baked egg/cow milk challenges under medical observation), repeat SPT/ssIgE to determine if the child potentially has outgrown their allergy (which is then confirmed with a food challenge), and in those deemed at higher risk of anaphylaxis, an adrenaline auto-injector is prescribed. Action plans must also be provided. Desensitisation to food allergens is still under research and still not yet in clinical practice.
IgE mediated cow’s milk allergy
If IgE mediated cow’s milk allergy is confirmed (i.e. immediate clinical reaction to cow milk and positive SPT/ssIgE to cow’s milk)
|Reaction severity to cow milk||Age group||Formula/milk alternative|
|Mild-moderate (i.e. skin or GIT reaction only)||< 6 months of age
> 6 months of age
|Extensively hydrolyzed formula*
|Severe (anaphylaxis, i.e respiratory or cardiovascular involvement)||Any age||Amino acid formula***|
*This can be prescribed by a Paediatrician, Paediatric Gastroenterologist or Allergist.
**In older children (> 12 months of age), rice/almond milks may be an alternative but it is important to note this are poor sources of protein and should only be used after discussion with the doctor/dietician.
***This can only be prescribed by a Paediatric Gastroenterologist or Allergist.
It is important the following milks are not given to those with IgE mediated cow milk allergy due to the risk of reacting to such milks/formulas
- A2 milk, lactose free milk
- Goat or sheep milk
IgE mediated cow milk allergy generally has a good prognosis, and on average 30% of children outgrow this allergy by 3 years of age, 50% by 5 years of age, and 90% by > 10 years of age. This is determined by performing the SPT/ssIgE every 12-18 months, and once the test result is low, under the guidance of an Allergist cow milk protein is then introduced back into the diet.
Skin Prick testing at Offspring
Skin Prick Testing is now available at Offspring. Patients will be required to make an appointment for this service that will be performed under the supervision of an Allergist/Immunologist. Patients will be provided with a written report documenting the results of the test as well as further information sheets about relevant allergen avoidance where appropriate. A report with the results will also be forwarded to the referring doctor. For patients intending to undertake a skin prick test, please do not take antihistamines for at least 5 days prior to your appointment as this will interfere with SPT and therefore this will not be able to be undertaken. Finally, for parents of young children your appointment may take up to 2.5 hours, so please ensure you come prepared.
- Congratulation Dr Sarah Donoghue for you latest article “Advances in genomic testing” in AFP April 2017.
- Congratulations Dr Jeremy Rajanayagam on your two presentations relating to Inflammatory Bowel Disease and Autoimmune Hepatitis in Prague, at the 2017 annual meeting for the European Society of Paediatric Gastroenterology, Hepatology & Nutrition (ESPGHAN).
- We would like to welcome Dr Sarah Condron to our team of Offspring Surgeons.