Friday Dr Q&A with Dr Liew – Elimination Diet and Allergy Test

Dr Liew Woei Kang

Marcie, who inspired MarcieMom to start this blog, doesn’t have any allergy and thus, this blog has been focused on eczema. Recognizing that there are many parents whose child also have allergy, MarcieMom invites Dr Liew Woei Kang, Paediatrician with special interest in Allergy, Immunology & Rheumatology to share more about managing allergy for eczema children.

More about Dr Liew: Dr. Liew practices at the SBCC Baby & Child Clinic and is also a visiting consultant to KK Hospital. He was also awarded several research grants from the National Medical Research Council, Singhealth Foundation and KKH Research centre to pursue clinical research in paediatric anaphylaxis, drug allergy, primary immunodeficiencies and Kawasaki disease. He is also the President of Singapore’s Asthma & Allergy Association which is currently administering the very first eczema fund (initiated by MarcieMom’s donation) for low income patients in Singapore.

MarcieMom: Last week we talked about allergy testing and today’s questions are follow-up on what parents can do as a follow-up to the tests. Given that allergy tests are not 100% accurate, parents may start to rely on an elimination diet strategy. Can you explain how much you would rely on each allergy test and whether they serve a different purpose in your diagnosis?

Dr Liew: Standard allergy tests are accurate, but as mentioned last week, have their limitations. Unvalidated tests for food allergy include blood IgG testing, intradermal skin testing, applied kinesiology, electrodermal testing, hair mineral testing, and iridology, and should not be performed. Eczema is a chronic medical condition with no curative treatment currently, and some patient would undertake extreme measures to look for the “elusive trigger”. I would remind your readers that eczema is a skin disease, and not an allergic disease. Removing triggers can reduce the eczema, but will not cure it.

Empiric food elimination may be considered for 2-3 weeks if a consistent food trigger is suspected. An objective assessment should be made if food elimination has resulted in any change. Food triggered eczema would improve significantly with elimination. If there is no improvement, as in the majority of cases, the food should be introduced and assessment made if there is a change. I would caution regarding multiple food elimination as I have seen really malnourished and stressed out patient and families.

MarcieMom: I understand that it’s good to send the child for a re-test, to check if he or she has outgrown any allergy or developed new ones. What’s the reason for the change in the allergy profile of the child? Also, how often do you recommend a re-test and would your recommendation differ for a child who has different type of allergies and/or differ for a child who has different level of severity in eczema?

Dr Liew: Retesting is sometimes required in food allergies, but generally not necessary for eczema. The allergic profile of an individual changes according to his/her immunity and exposure to environmental proteins. We often see food allergens being “outgrown”, but a gain of house dust mite sensitisation with time. Retesting is usually considered if there is a new allergic disease eg. Allergic rhinitis, rather than based on fluctuation in eczema severity.

MarcieMom: Thank you Dr Liew; the advice you just shared is so useful as many parents, like myself, while struggling and managing with eczema in our children would have wondered if we ought to eliminate certain foods or bring our child for another test!

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  1. Thanks for commenting again! The first sentence of his reply seems to be in the context of children with eczema, as I’ve asked the question on re-testing based on eczema severity. And yes, I’ve read also in some articles that retesting can be done at 3 year old 🙂 Hope your child outgrow many of the current allergens, so that more yummy food can be enjoyed!

  2. This is a great post.

    I don’t know about Liew’s answer to the last question. We get healthcare from Kaiser Permanente in the US and their policy (at least in our case) was a battery of skin prick tests at 1 year with retesting at 3 years, presumably because there can be significant changes. Our kid tested positive to so many allergens (she had both skin & digestive issues) that we are eager to find out if she can now tolerate some major food groups. From what I’ve read, the allergic profile changes the most over the first three years or so. Liew has personal, professional experience with this; if he says “we often see food allergies being outgrown,” then it makes sense to retest.