What if the Prick test is the *first* exposure to an allergen? - Mothering Forums

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#1 of 16 Old 09-24-2009, 11:07 AM - Thread Starter
 
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Hi everyone,

I don't generally hang out in the allergy forum, despite my having a peanut/walnut allergic son, but I have a question and I'd like to get all the information I can before I call the allergist.

As I said, DS1 is peanut/walnut allergic. On the recommendation of the allergist, I took DS2 to be checked for a peanut allergy the last time we had an appointment, to rule it out.

He turned out to test negative--so I thought, great! But then I started thinking: what if the prick test was his first exposure to the allergen? As far as I've heard, often the first exposure to an allergen does not provoke symptoms, but the body "gears up" for the next exposure. Would this confound the test results? We don't give any of the kids peanut/tree nut products, so this would be the first time that DS2 would be exposed. Now I feel like I need to confirm the results with a second test, or at least talk to the allergist about it.

So if anybody has any thoughts, I'd love to hear them. All the information I can get is very welcome, and thanks!

Sara (smilie at the request of my kids: )
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#2 of 16 Old 09-24-2009, 03:05 PM
 
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nak
i'd call my allergist bc i have no idea!
great question.

Wife of Michael , SAHM to Aristotle 09/99 Raphael 06/07 and Marius 05/09 Known only in dreams but never forgotten: Euphrates Decluttering 290/2010
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#3 of 16 Old 09-24-2009, 05:31 PM
 
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Quote:
Originally Posted by larastheme View Post
Hi everyone,

I don't generally hang out in the allergy forum, despite my having a peanut/walnut allergic son, but I have a question and I'd like to get all the information I can before I call the allergist.

As I said, DS1 is peanut/walnut allergic. On the recommendation of the allergist, I took DS2 to be checked for a peanut allergy the last time we had an appointment, to rule it out.

He turned out to test negative--so I thought, great! But then I started thinking: what if the prick test was his first exposure to the allergen? As far as I've heard, often the first exposure to an allergen does not provoke symptoms, but the body "gears up" for the next exposure. Would this confound the test results? We don't give any of the kids peanut/tree nut products, so this would be the first time that DS2 would be exposed. Now I feel like I need to confirm the results with a second test, or at least talk to the allergist about it.

So if anybody has any thoughts, I'd love to hear them. All the information I can get is very welcome, and thanks!

Sara (smilie at the request of my kids: )
with regards to tree nuts, or peanuts, isnt is likely they were exposed through some product already? they are in so many things...

Heavily tattooed and Dready Mama to my girls. YES we are STILL NURSING! love to and
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#4 of 16 Old 09-24-2009, 05:32 PM
 
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Originally Posted by inkedmamajama View Post
with regards to tree nuts, or peanuts, isnt is likely they were exposed through some product already? they are in so many things...
In general- that would be true. In this case the OP has a nut-free house due to another child who is allergic...

Good question... wondering myself.

-Angela
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#5 of 16 Old 09-25-2009, 02:15 AM
 
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I agree with alegna. Normally, I'd say he'd probably have been exposed given the prevalence of peanut but given he is in a nut free house, I'd really wonder too. Let us know what you find out!

Maybe you could get a blood test for IgE antibodies (immediate reaction) as well?

Me (37) ~ DH (39) ~ DS (3) ~ TTC #2 since 4/10
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#6 of 16 Old 09-25-2009, 08:49 AM - Thread Starter
 
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I've got a call in to the allergist. I'll update when I hear back. Thanks, everybody!
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#7 of 16 Old 09-26-2009, 01:17 PM - Thread Starter
 
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Well, the allergist doesn't think that the lack of previous exposure would confound the test results, but I have my doubts, since it took me a *long* time to explain to her what I meant. In fact, she told me that I was overthinking it (sorry, but a potential peanut allergy is something to be sure you understand.)

She gave me something about a localized vs. systemic reaction making the difference between the two (a systemic reaction requires a first exposure to "prep" the body for the second exposure, but localized reaction doesn't work that way? The IgE cells simply react locally but not systemically with a first exposure?)

And with the standard caveat that any allergy can develop at any time, now I'm simply wondering why I bothered having him tested! It's a little frustrating. Anybody know if the blood test would be any different?

I don't intend to feed him peanuts for now anyway, since we keep a peanut/nut-free home, but it would be nice not to wonder for the future.

Thanks for listening to my rant. back to your regularly scheduled programming...
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#8 of 16 Old 10-02-2009, 06:04 PM
 
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This is an interesting thread. My 10yo claimed to not like nuts, though she had never tasted them. My dh was on a kick of getting dd to try new foods and had her eat a walnut. Her mouth got just a bit itchy, which is not out of the ordinarly since dd has Oral Allergy Syndrome (which does not carry an anaphalaxis risk.) When she was skin tested shortly afterwards at the allergist, the result was inconclusive. The walnut reaction was larger than the saline control, but smaller than the histamine control. A blood test showed a low level allergy. A followup skin test quite conclusively showed an allergic reaction to walnut this time!
Perhaps go for a second opinion if you are concerned?
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#9 of 16 Old 10-03-2009, 12:11 AM
 
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Did you eat any nuts while pg?

Jennifer, LPN and nursing student, Doula, CPST, and VBAC mama x3 to
AJ (5/03), Evan (12/04), Ilana (11/06), Olivia (2/09), and Unity (8/2012)

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#10 of 16 Old 10-03-2009, 11:35 AM - Thread Starter
 
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I may have had a *low* level pf peanut while pregnant with DS2, I honestly don't think I ate peanut butter, but I may have had some in other products. That was something I wondered about, too: does the peanut (or other allergen protein) cross the placenta whole and unchanged enough to cause a sensitization/reaction? I mean, if I ate peanuts while pregnant with a peanut allergic child (DS1, for instance), would the first exposure cause sensitization and then the second time I ate peanuts, would the baby have a "reaction" in utero? It doesn't make sense to me (perhaps I am, after all, overthinking it.)

Ack26, thanks for the story. So, to clarify, the tests were done after she ate a walnut, right? The first was inconclusive, then both blood tests and skin testing showed allergy. Then I suppose she had the opportunity to be sensitized with that first exposure. But the stinky test didn't show it the first time. (What made you have her get a blood test? Did the allergist do them at the same time?)

I guess that just illustrates something that makes allergies such a difficult thing to control/diagnose/whatever: even the testing kinda stinks. Sure, I wish I didn't have to deal with it, but since I do, I want to know everything I can. Maybe I will try to get DS2 tested via blood, but I hate to since he's only 16 months old. More to consider.
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#11 of 16 Old 10-04-2009, 10:19 PM
 
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[QUOTE=larastheme;14473808]

Ack26, thanks for the story. So, to clarify, the tests were done after she ate a walnut, right? The first was inconclusive, then both blood tests and skin testing showed allergy. Then I suppose she had the opportunity to be sensitized with that first exposure. But the stinky test didn't show it the first time. (What made you have her get a blood test? Did the allergist do them at the same time?)
QUOTE]


Yes, the tests were done after she had a (non-anaphalactic) reaction to eating one walnut. The blood test was ordered because the skin test wasn't clearly negative nor clearly positive. The reaction to the walnut syrum(?) was more than the control of plain saline. There was a reaction. But it wasn't as large as the control of pure hystemine, so it wasn't enough of a reaction to be positive for an allergy. Nut allergies can be life-threatening, so inconclusive was not enough for the allergy to clear dd of an allergy. The next step was the blood test which did show an allergy. The second skin test was because I went to a different allergist for a 2nd opinion. That skin test came back as a very clear positive for walnut allergy. Did that help clarify at all?
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#12 of 16 Old 10-09-2009, 01:35 PM
 
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Insider had some very interesting posts in the "How not to have an allergic child" thread which I believe he said that food proteins can hang around in the mother's body even if she doesn't eat them presently?

You sound like me, I "overthink" (translating = think carefully using my mama wisdom ) things too. Personally this is what I have always thought was a risk to doing prick tests in a documented atopic child. How old is your DS2? Does he have any atopic sx?
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#13 of 16 Old 10-09-2009, 06:42 PM - Thread Starter
 
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Originally Posted by JaneS View Post
Insider had some very interesting posts in the "How not to have an allergic child" thread which I believe he said that food proteins can hang around in the mother's body even if she doesn't eat them presently?

You sound like me, I "overthink" (translating = think carefully using my mama wisdom ) things too. Personally this is what I have always thought was a risk to doing prick tests in a documented atopic child. How old is your DS2? Does he have any atopic sx?
No symptoms at all, he's 16 months old. We had him tested because of the predilection (10% higher chance?) for younger siblings of peanut allergic kids to have their own peanut allergy. Interesting idea that the proteins hang around for some time. More to think about
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#14 of 16 Old 10-11-2009, 10:06 PM
 
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Just to give you our story. My DS is allergic to nearly everything and was no foods from 10-20 months old. When he was allergy tested, some foods came up positive and some came up negative. The interesting thing we noticed was the foods he was eating before we took him off food were all positive, but the foods he had never eaten were all negative.

He started doing in-hospital food trails for his negative foods and he was failing all of them. He had a negative skin prick test prior to eating the food, he ate the food and failed it, and then they did the skin prick test again and it would be positive. So yes, I believe you can be negative due to lack of exposure and then an exposure would lead to a positive test.
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#15 of 16 Old 10-12-2009, 12:31 AM
 
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Originally Posted by JaneS View Post
You sound like me, I "overthink" (translating = think carefully using my mama wisdom ) things too. Personally this is what I have always thought was a risk to doing prick tests in a documented atopic child. How old is your DS2? Does he have any atopic sx?
Yes, this is why I did not do a skin prick test for my child, whom I already knew to be allergic to peanuts. We discovered by accident, and it was clearly peanuts.

I think what I would do is just avoid all peanuts and nuts anyway, since you're already doing it for the other child, and at 16 months he doesn't know the difference. I have read that the blood tests are not very accurate when they are that young. I would just wait and then you can decide when he's older and maybe have a blood test then.
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#16 of 16 Old 10-12-2009, 01:15 PM - Thread Starter
 
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Yes, this is why I did not do a skin prick test for my child, whom I already knew to be allergic to peanuts. We discovered by accident, and it was clearly peanuts.

I think what I would do is just avoid all peanuts and nuts anyway, since you're already doing it for the other child, and at 16 months he doesn't know the difference. I have read that the blood tests are not very accurate when they are that young. I would just wait and then you can decide when he's older and maybe have a blood test then.
Right, I intend to avoid peanuts anyway, since it's the way we live, but not knowing if he is, in fact, allergic is tough.

Delaney21, *thank you* for your story. It really helps me to hear something like that, in a hospital setting, no less. Were you given any reason for the reactions happening like that after negative skin pricks? I hope you weren't told that "allergies can happen at any time" (the standard disclaimer, it seems, for allergists and the failure of their tests to accurately predict allergy.)
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