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 Post subject: false positives?
PostPosted: Mon Sep 18, 2006 10:43 am 
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Joined: Wed Sep 13, 2006 10:59 am
Posts: 63
Location: Ohio
How often are the results from RAST tests false? I found out my son was allergic to wheat, soy, milk, eggs, peanuts, and oats after he had a reaction to a wheat cracker. Someone told me that they thought if you get tested right after a reaction that occaisionally it will lead to false positives? Does this make any sense to anyone? Has anyone ever been tested after a reaction and then again later to find the test yielded different results.

Just trying to get a handle on this info.....

Thanks!

_________________
2.5 year old: allergic to wheat, dairy, egg, peanut, oat, turkey, and cats
5 year old: no known allergies
Husband no known allergies
Me allergy to morphine only


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 Post subject:
PostPosted: Mon Sep 18, 2006 11:09 am 
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Joined: Tue Sep 12, 2006 8:25 pm
Posts: 233
Location: Winnipeg
My son had a positive to wheat on his RAST, although he eats wheat every day and has never had a reaction to it (our pediatrician said it could be because he is allergic to grass pollen? Have yet to finish his environmental testing with allergist.)
We have also had false negatives before. Such as when my other son had a negative RAST for dogs, even though he gets very ill any time he is around one and will break out in huge angry hives if one licks him.
Our allergist said that RAST testing is not particularly accurate on it's own, but is used in conjunction with skin testing, and most importantly observations about what actually happens in real life to help paint a picture of what our allergies are and how severe they may be.
Hope that helps.

_________________
1 son allergic to eggs, peanuts, green peas, chick peas, lentils and tomatoes
(avoiding tree nuts and most other legumes too)
1 son allergic to eggs, and has outgrown peanuts
Both with many environmental allergies, asthma and eczema


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 Post subject:
PostPosted: Mon Sep 18, 2006 11:22 am 
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Joined: Wed Sep 13, 2006 10:59 am
Posts: 63
Location: Ohio
That does help thank you.

Another question: So if a child is allergic to peanuts that doesn't necessarily mean the reaction will be full ana?

My son's reaction to a wheat cracker was swelling, hives, runny nose, trembling, etc but no compromised airways. the allergist told me that wheat doesn't typically produce a full anaphylactic response but egg and peanut can.

How do you know if he has a contact reaction? I don't want to put peanuts anywhere near him. I wish there was someway I could predict his response to the foods he is potentially allergic to...

_________________
2.5 year old: allergic to wheat, dairy, egg, peanut, oat, turkey, and cats
5 year old: no known allergies
Husband no known allergies
Me allergy to morphine only


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 Post subject:
PostPosted: Mon Sep 18, 2006 12:30 pm 
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Joined: Tue Sep 12, 2006 8:25 pm
Posts: 233
Location: Winnipeg
Unfortunately, the problem with allergies is that they are unpredictable.
That sounds like a fairly serious reaction that your son had. And though I'm definitely no expert, it's my understanding that reactions can get worse with repeated exposures. So if he was to be exposed to wheat again it could be an even more serious reaction.

As far as peanuts are concerned, I know that they can progress from a mild to an anaphylactic allergy. I would be careful, and keep him away from any contact with peanuts.
We had a similar situation with both my sons, when they were two their RAST's came back showing just under positive /low positive to peanuts. But I noticed that even when someone else ate PB and then touched or kissed them, they would get a few hives. And even though we've kept their diets peanut free, their latest RAST and skin testing showed both positive for peanuts, one low and one of them is high. Which means he would likely have an anphylactic reaction if exposed.
So yes, peanuts and eggs (one son had an ana reaction to eggs last year, it was very scary) can be extremely dangerous allergies. But I would be careful with any allergy, especially for such a little guy.
As far as contact reactions we've had mild ones (a little sniffly, a little rashy), and serious ones (covered in hives ,swollen hands, ears, asthma etc.). Other children have had ana from contact. The trouble is that when you have severe allergies, any place or situation can be dangerous, and you can really drive yourself crazy! We are sticklers for handwashing and carry wipes with us wherever we go. We never leave home without epipens, benadryl and asthma puffers, whether we plan on eating or not, because you just can't avoid contact with allergens all the time no matter how careful you are.
And I know it's kind of lame to finish all that off with, don't worry. But really it will be OK. You are already reaching out for support and finding good information (this forum is full of it. I'm a new member here too, and I'm finding it such a help!). I remember how overwhelmed and scared i felt about my sons' allergies when they were babies, and I sometimes still feel that way (starting school is hugely stressful), but we've made it this far :lol: ! And they really are very normal, active, happy little kids.

_________________
1 son allergic to eggs, peanuts, green peas, chick peas, lentils and tomatoes
(avoiding tree nuts and most other legumes too)
1 son allergic to eggs, and has outgrown peanuts
Both with many environmental allergies, asthma and eczema


Last edited by twinmom on Mon Dec 04, 2006 3:21 pm, edited 1 time in total.

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 Post subject:
PostPosted: Mon Sep 18, 2006 12:34 pm 
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Joined: Tue Sep 12, 2006 8:25 pm
Posts: 233
Location: Winnipeg
One more quick thing about contact, BEWARE OF SHOPPING CARTS! They have to be one of the worst offenders for spreading allergens, and everything else. Wipe them down with lysol wipes or don't put your son in them at all.

_________________
1 son allergic to eggs, peanuts, green peas, chick peas, lentils and tomatoes
(avoiding tree nuts and most other legumes too)
1 son allergic to eggs, and has outgrown peanuts
Both with many environmental allergies, asthma and eczema


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 Post subject:
PostPosted: Mon Sep 18, 2006 2:22 pm 
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Joined: Sat Apr 16, 2005 12:09 am
Posts: 1054
Daisy talks about false positives and false negatives with RAST tests here too:
http://www.allergicliving.com/forum/vie ... c&start=15

Not every person allergic to peanuts is anaphylactic. I believe that having asthma does put someone at greater risk. A high number on the RAST does not mean you will have a greater or more severe reaction -- it simply indicates that some reaction will happen - whether it be hives, wheezing, or a full blown anaphylactic reaction. (Additionally previous reactions will not necessarily reflect future reactions -- it's a guessing game and it's why it's so important to always have epinephrine on hand if needed)

Ditto to the shopping cart warning that twinmom gave -- with young allergic children I don't believe it's worth the risk if you can avoid it.


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 Post subject:
PostPosted: Mon Sep 18, 2006 3:11 pm 
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Joined: Tue Sep 12, 2006 8:25 pm
Posts: 233
Location: Winnipeg
Good to know that the RAST number doesn't indicate potential severity of the reaction. My pediatrician, seemed to think he was at risk for a serious reaction, maybe it is the tie in with the asthma that she's using as an indicator.
Gosh, it's a lot to take in sometimes.

_________________
1 son allergic to eggs, peanuts, green peas, chick peas, lentils and tomatoes
(avoiding tree nuts and most other legumes too)
1 son allergic to eggs, and has outgrown peanuts
Both with many environmental allergies, asthma and eczema


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 Post subject:
PostPosted: Mon Sep 18, 2006 8:16 pm 
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Joined: Thu Sep 22, 2005 11:39 pm
Posts: 1141
Location: saskatchewan, canada
My youngest has also had a shopping cart reaction. Also...if you do go to a restaurant with your youngest...even if you do not plan on feeding anything you have not brought yourself...DO NOT put your child in the restaurants high chair :oops: . We did that when we were new to this..now we don't go to restaurants.

_________________
DD age 9 1/2 -peanuts, nuts,
DD age 7 1/2 - milk, eggs, chicken, peanuts, treenuts, cats, dogs,
DS age 2 1/2
Husband- asthma, eggs, treenuts, fish, shellfish environmental
Self - penicillan, eurithromiacin, mild laytex allergy.


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 Post subject:
PostPosted: Wed Sep 20, 2006 1:10 pm 
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Joined: Wed Sep 13, 2006 10:59 am
Posts: 63
Location: Ohio
So when you say they had a shopping cart reaction, what happened?

When we take Sam to restaurants we always wipe down the high chair and table but sometimes he gets a little rash on his skin where he made contact (backs of his legs or his forearm, etc). It is nothing serious and doesn't bother him but it does make us think about how something is causing him to reacte, even if we can't see it (e.g., no crumbs or food is visible).

_________________
2.5 year old: allergic to wheat, dairy, egg, peanut, oat, turkey, and cats
5 year old: no known allergies
Husband no known allergies
Me allergy to morphine only


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 Post subject:
PostPosted: Wed Sep 20, 2006 2:04 pm 
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Joined: Wed Sep 13, 2006 10:59 am
Posts: 63
Location: Ohio
Ethan's mom- thank you for the link. That was very helpful. I am also encouraged by the discussions about finding a "cure" for PA in the future!

_________________
2.5 year old: allergic to wheat, dairy, egg, peanut, oat, turkey, and cats
5 year old: no known allergies
Husband no known allergies
Me allergy to morphine only


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 Post subject:
PostPosted: Wed Sep 20, 2006 3:36 pm 
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Joined: Thu Sep 22, 2005 11:39 pm
Posts: 1141
Location: saskatchewan, canada
My youngest was COVERED in hives after sitting in a shopping cart. And again, from the restaurant high chair. Even though it was not an emergency situation...the idea that she was being exposed...and could cause her reactions to worsen in the future was enough for me to want desperately to avoid those situations. I mean...if they are more likely to outgrow the allergy from strict avoidance I certainly don't want contact reactions interfering with that. It is just not worth it.

If you are still doing restaurants...I would suggest bringing your own booster seat (with tray) from home to put on the restaurants chair...and then NOT using that booster seat (which has been in a restaurant environment) at home in your clean "safe" eating area. As well as feeding only foods prepared at home.

There are a few people who post here whose kids have had an anaphylactic reaction from sitting in a shopping cart.

_________________
DD age 9 1/2 -peanuts, nuts,
DD age 7 1/2 - milk, eggs, chicken, peanuts, treenuts, cats, dogs,
DS age 2 1/2
Husband- asthma, eggs, treenuts, fish, shellfish environmental
Self - penicillan, eurithromiacin, mild laytex allergy.


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