False Positives

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BeckyHyland
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Joined: Mon Feb 09, 2015 11:14 pm
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by BeckyHyland on Mon Feb 09, 2015 11:28 pm

False Positives

My son tests positive to most foods (IGE RAST tests), some are known to cause immediate issues but many of the others he "seems" to cope with (bar potential eczema/itching flare up). What makes the body sensitise themselves to these foods and how come only some are true positives? Do you feel he would still remain at risk to all these foods, given he is sensitised in a significant way? I'm just trying to understand why his body picks & choses which of these sensitised foods will actually result in a reaction? Thank you.

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Dr Anton Alexandroff
Posts: 435
Joined: Tue Sep 18, 2012 9:11 am
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by Dr Anton Alexandroff on Tue Feb 10, 2015 1:30 am

Re: False Positives

Dear BeckyHyland,

Thank you. RAST test is not always helpful. Children and adults may have positive RAST test(s) and still may not react to foods. Similarly children and adults may have negative RAST test(s) but still may react to antigens, although this is arguably less likely. RAST test is interpreted in a combination with history of past reactions and food diaries by specialists.

Please kindly note that if you suspect a dangerous reaction like nut allergy you should not do food challenge at home but you should seek first advice from your family doctor.

RAST test is more relevant to urticaria (nettle rash) and anaphylactic type of reactions, whereas patch test (done by dermatology specialists) is more relevant for eczema and dermatitis.


I hope this is helpful.
with best wishes,

Dr Anton Alexandroff MRCP (UK), CCT (Dermat), PhD, FRSM, FAAD
Consultant Dermatologist
University, Nuffield and Spire Hospitals of Leicester
for more information on skin conditions and treatments see www.alexandroff.org.uk

twitter: @your_skin_dr

blog: http://privatehealthnews.co.uk/category ... rmatology/
Dr Anton Alexandroff
Consultant Dermatologist, Honorary Senior Lecturer & BSF spokesperson - FRCP, CCT (Derm), PhD, FRSM, FAAD

http://www.talkhealthpartnership.com/on ... ndroff.php

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