Talking Allergies

False positive on skin prick ?
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Author:  EmilyTricia [ Tue May 10, 2011 11:40 pm ]
Post subject:  False positive on skin prick ?

Well, my just turned 6 year old son went in for his annual skin prick test. To find out he is now a 1+ for hazelnut and a 2+ for pistachio and some other nut we never eat so I can't remember the name : ) Anyways, problem is, my son eats a hazelnut spread pretty near every day of his life. When I told this to his allergist he just said, maybe it's a false positive then. He never told us to avoid hazelnut. Then he quickly left the room. Leaving me standing there, wondering what just happened. And wondering about the accuracy of these tests. I was reading that the skin prick test can have a 50% false positive result.
To give some history, my son, who has mild asthma was tested for allergies at 3 years of age to see what his triggers might be. We never suspected food allergies. My husband and myself are not allergy sufferers. When peanut and shellfish came up we were very surprised. I told the allergist at this time that my son had regularly eaten peanut and had never had a reaction but no food challenge was set up at this time. He did not react to any nut mix or tree nut, nor did his rast show a tree nut allergy.
When my son was 4 we went in again for another skin prick test - peanut had no reaction - shellfish although present, a less reaction. He finally set up a food challenge to peanut as his RAST test also showed negative response. At 4 years old he still showed no reaction to tree nut. He passed his food challenge for peanut. Although trying to get him to eat anything with peanut in it is challenging - to say the least. So I'm having doubts if he was ever really allergic to peanut... Maybe a false positive result perhaps then too? I guess my question is - how much weight should we give these tests if these foods are being eaten and tolerated? Or should we just accept that even at 1+ we should completely avoid the food until a further allergy tests says otherwise???

DS - mild asthma, allergic to shellfish, and apparently some tree nuts / outgrown peanut allergy.

Author:  BC2007 [ Wed May 11, 2011 6:42 am ]
Post subject:  Re: False positive on skin prick ?

Welcome Emily, so glad you found us at A.L. forum. :huggy

Wow, that is a lot of testing done for foods he was never reacting to when eating. :scratchy I am not a scientist or a dr. so I only say what I would do in my own personal experience. If your son is eating foods..with NO reaction in my opinion there is no need to now stop eating them. Why limit his diet and avoid foods he has eaten for years now with no issue, some as you mentioned daily (hazelnut spread). I know someone who while at her son's allergist had herself tested randomly and her sp's shows allergies to all kinds of foods, foods she's eaten for 30 yrs with no reaction. I don't in her case know why an allergist would test either if there is no food reaction. :scratchy
I know your allergist is trying to find a cause for your son's asthma flares ups but digging for food allergies when he isn't at this time reacting to food seems pointless..IN MY OPINION!!

So I wouldn't worry about food, let him eat what he has been eating. Focus on asthma triggers beyond food.... I think there is an article somewhere about how food allergies are diagnosed through reaction to the food then confirmed by skin prick/rast if necessary. I'll see if I can find it in the A.L. saved articles.

Has your allergist looked at other reasons your son's asthma might be flaring. Our son had awful asthma due to ear infections/colds. He asthma also was triggered this year by snow mold (new to me), triggers are also all his environmental allergies all spring/summer. Could something as simple as scent of some sort or his bedding be bothering your child? A pet at daycare?

Does he have environmental allergies (dust, dander, trees etc.) which could be triggering his asthma?
Is his asthma action plan/meds not sufficient to keep him stabalized?
Have you seen an asthma educator to see his meds are being given to get max. benefit from them. This is not meant to be critical, I think I read 1/2 of us use the puffers etc. incorrectly. I know I wasn't waiting long enough between puffs and wasn't shaking enough before giving them to please don't take that the wrong way.

There are lots of great mom's on here who are seasoned pro's when it comes to asthma. I hope your little one is feeling better.

Author:  _Susan_ [ Wed May 11, 2011 10:39 am ]
Post subject:  Re: False positive on skin prick ?

Because of the potential for false positives and the desire to restrict the diet as little as possible, most allergists will not test a food unless it is thought to have provoked a reaction in the past.

Why is your Dr testing for foods which are currently tolerated? I would get a second opinion.

Author:  EmilyTricia [ Wed May 11, 2011 11:47 pm ]
Post subject:  Re: False positive on skin prick ?

Thanks so much for the guidance. It's all appreciated. My biggest concern is the food allergies, as we do seem to have his asthma completely under control. He is allergic to dust mites and cat dander too and we took him to the asthma clinic at our hospital to help us figure out an action plan for him. It'd be nice if they had a food allergy clinic too - but they fall short on that one. Just wondering if anyone can suggest an allergist for a second opinion? When I took my son in for the initial visit the allergist did a general skin prick and testing not only for enviromental but also some food. I never mentioned any food reactions to him so I figured this was just a normal test. I was concerned that he didn't seem to consider my son's past history about being able to tolerate peanut - he just said to avoid them after the skin prick results. Then after leaving his office and doing my own on-line research, everywhere it says the the food challenge is the gold standard for determining food allergy - yet, here we are at home passing the gold standard daily. The lack of direction from the Allergists we've dealt with has been - in my opinion negligable. If it weren't for the internet I'd be completely lost. And now I've got to make the decision to get my second son, who just turned 3 tested for allergies - or Not ??? I guess because my 6 year old does seem to be allergic to shellfish - he didn't tolerate shrimp when he ate them for the first time he experienced nausea and vomitting, maybe I should test my younger son - but am concerned he may have a false positive result too - limiting what we feed him. He has never had shellfish as we don't eat it at home now - and peanut is limited too.
Anyways if you can make a recommendation on this site for a great allergist - I'd love to have it !
Son - allergic to shellfish, cat dander, dust mites, some tree nuts.
ourgrown peanut

Author:  Alison's Mom [ Thu May 12, 2011 1:27 am ]
Post subject:  Re: False positive on skin prick ?

It does all sound very confusing, and also it's unfortunate your allergist hasn't been able to provide more information to you.

I didn't see where you mentioned what city you were in? If you let us know, perhaps we will be able to let you know of some good allergists nearby.

Author:  Becky [ Thu May 12, 2011 9:27 am ]
Post subject:  Re: False positive on skin prick ?

After the negative oral peanut challenge I assume the Dr gave the Ok to consume them? I would think hazelnut would fall under the same category? From everything I have read, and from talking to Drs & allergists oral challenge/history always supercedes skin or rast testing. Good luck!

Author:  EmilyTricia [ Thu May 12, 2011 9:57 am ]
Post subject:  Re: False positive on skin prick ?

I am in the York Region Area - but for a recommended allergist, I don't mind travelling anywhere within the GTA - Toronto.

Author:  EmilyTricia [ Thu May 12, 2011 10:19 am ]
Post subject:  Re: False positive on skin prick ?

Yes, the Allergist gave the green light for him to eat Peanut after the oral food challenge. But... do you think I can get this kid to eat anything with peanut in it ?? And he absolutely hates peanut butter. I even tried to put a very small amount on a piece of toast and then cover it up with a lot of Nutella and he still picked the flavour out and refused to eat it. :banghead

Anyhow, they say to keep trying or he may become sensitive to peanut again. :thumbsup

I guess that's a topic for another discussion... "How to re-introduce foods we once told our chidren to avoid eating at all costs."

So, I am presently allowing my son to continue to eat Nutella - however, on the days he goes to school I will not feed him nutella - as I want to keep a close eye on him now after eating it. Paranoia perhaps.?!? But isn't that the life of a parent with a food allergic child....

Author:  _Susan_ [ Thu May 12, 2011 11:32 am ]
Post subject:  Re: False positive on skin prick ?

Buy peanut M&M's and tell him it's Dr's orders that he eat what? 4? per day. You wouldn't take "No"
for answer with any other medical treatment. That is what this is.

Author:  _Susan_ [ Thu May 12, 2011 10:59 pm ]
Post subject:  Re: False positive on skin prick ?

But, she did state her son passed an oral challenge for peanut.

Author:  EmilyTricia [ Fri May 13, 2011 11:12 pm ]
Post subject:  Re: False positive on skin prick ?

Well, I really have tried to feed him peanuts. He absolutely refuses. Even after I've explained to him all the reasons why he should. He is a very smart 6 year old. I have tried to hide it in things and he can always pick it out. He absolutely hates the taste. So, failing sitting on him and forcing it down his throat I cannot get peanut into him.
But I'm getting off topic here... after reading some other allergy sites blogs - seems some people have reported eating a food they have been told they have an allergy to - but not believing it as they have eaten it in abundance in the past only to have a reaction 10 years down the road. So, it's making me rethink the Nutella thing - maybe a rast test will confirm some numbers for me and give me some direction? Anyone know how accurate they are ? I've read they can be unreliable too. : (

Author:  _Susan_ [ Sat May 14, 2011 7:43 am ]
Post subject:  Re: False positive on skin prick ?

Besides the forum, facebook and magazine, Allergic Living also has many articles on it's webpage. Click on one of the tabs to open a menu on that subject.

Here's an overview on food allergies and various tests: ... allergies/

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