Best Test for Food Allergies? Article by Dr Wood

Thanks. What I would like to know, is what would be the best test for my kids who have never had any exposure to any type of nuts. They have had cap-rast testing which was negative, but we were then told by the allergist to continue to avoid (my oldest does have PA/TNA-this was for my younger two) since the possibility of a false negative could be high due to the fact that they had never had an exposure (thus possibly no IGE in their blood *yet*). I was curious why he even agreed to do the test if it was that unreliable with no prior exposures. We're going on a driving trip for vacation this summer and eating out pretty much the whole time. I worry that if something was to cause a reaction in our older dd, then what if one of the younger two (or both) were also allergic-they would have a reaction too and with only two epi-pens on hand. Either way I'm going to get two more pens for vacation one way or another so we always have 4 on hand.

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[b]~Gale~[/b]

I do recall one of our allergists saying that he has seen children react to peanuts even with a negative rast test.

I think that negative skin tests are pretty reliable but I dont think either test can give you an answer with 100% certainty.

The book "Food Allergies for Dummies" does go into testing a great deal more than even the article. (I have nothing to do with the book but I do recommend it!)

My friend Nicole Smith's son (from AllergicChild) tested negative to fish and then had an anaphylactic reaction on a camping trip. Her son wrote about it in her newsletter and it was also an article in Allergic Living magazine.

I'm sure its unusual, but it happens.

Take care,
Gina

It has been my understanding that one must be exposed to the protein before actually becoming allergic. If your child has not been exposed at all, it is true that a RAST may come back neg. because they simply haven't been exposed yet. However, they wouldn't [i]already[/i] be allergic to a food if they have never yet been exposed to it.

How old are your younger children. Apparently, if they are older than 3 or 4 years old, the likelihood of becoming allergic is extremely low.

My dd had a negative skin test to egg at age 2 1/2. Then three days later she ate egg for the first time and had an anaphylactic reaction requiring epi.

Quote:Originally posted by MimiM:
[b]It has been my understanding that one must be exposed to the protein before actually becoming allergic. If your child has not been exposed at all, it is true that a RAST may come back neg. because they simply haven't been exposed yet. However, they wouldn't [i]already[/i] be allergic to a food if they have never yet been exposed to it.

How old are your younger children. Apparently, if they are older than 3 or 4 years old, the likelihood of becoming allergic is extremely low.[/b]

I have to disagree with this, from personal experience.

Caitlin RAST + to shrimp, lobster, crab, peanuts, all nuts, etc...

While PG with her, DW never ate them... while BFing, never ate them... AFAIK, while consuming things, Caitlin's NEVER had them.

Yet she RAST + to them.

How do I know that DW never ate them? She's allergic to them HERSELF.

I know it sounds weird, and maybe its not the 'norm', but I think you can test positive to anything even if you've never ingested.

HTH

Jason

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[b]* Beyond Obsessed * [/b]

I'm with Jason on this one. Both DS and DD are PA according to rast (class 6 and 5 respectively). By the time I was pregnant with DD, my son had been through anaphylaxis and officially diagnosed. Every precaution was in place and our home was completely nut free. Nevertheless, my daughter's rast has mysteriously climbed from a class 2 to class 5 through the last several years. It's very mysterious to me, and I would love to know what's actually going on, sensitization-wise. I don't believe this is the result of exposures, based on our experience.

I've said it before and I'll say this again....

MOST allergists feel that a negative test = 'no allergy' but this does NOT inlcude the possiblility that the child has truly never had any exposure. This happened to us with TN.

And though I know that what Jason is saying is true, I must say that there is a vast gap between "exposure" as in, you know it is happening and can identify the source of that exposure, blah blah blah, and [i]ultra-trace exposures which nevertheless serve to sensitize someone.[/i] Allergists are of the opinion that such exposure is [i]inevitable and UNAVOIDABLE[/i] and that this is why a negative skin test means 'no allergy' even when you say "But we've avoided."

This assumption can be wrong, BTW....

But so (IMO) is the statement that someone was sensitized without [i]any[/i] exposure. Sure, many PA people fly on airplanes and sit near PB+J all the time [i]without reacting.[/i] But does that mean there has been [i]no exposure?[/i] It does not, as people like my DD show. She reacts (like the proverbial canary) to many things that even other PA people wouldn't give a second thought to.

Very tiny, subclinical exposures are plenty to prime the immune system in someone who is genetically so inclined. In those cases, honestly, there probably is not any way to [i]prevent[/i] sensitization-- at least not and have anything resembling a normal lifestyle. Even by our standards. LOL!

(This is how I think kids like Jason's daughter were sensitized. Casual contact or aerosol contact which wasn't enough for even his DW to know it was there.)

Because mechanistically speaking, there really isn't a way for your immune system to make IgE for something it doesn't know about. But clearly the amounts needed to cause this 'sensitization' event in some kids are almost unfathomably small.

I know youre right Jason. I actually brought that up to our allergist who acknowledged that it happens (mom allergic and does not ingest allergens but baby is allergic.)

Gina

I would never doubt a positive cap-rast but it's the negative ones that I'm not sure are reliable. My younger dd may have been exposed in utero and through breastfeeding (I know I ate peanut butter when nursing before I knew not to but not sure if I did while pregnant). With my son I was careful not to eat peanuts, peanut butter, nuts, etc while I was pregnant and nursing, BUT I did eat a lot of sunflower seeds when I was pg with him (because I was sick all the time and they were the only thing that calmed my stomach) and they were the planter's type that had peanut oil. At the time I had been told at least two or three times, in writing and on the phone, by FAAN that peanut oil was not allergenic (I know now that may not be true) and it was after we took dd to an allergist (while I was pg with ds) that we were told to avoid it so even he *may* have been exposed in utero through that. No actual peanut or nut while I was pregnant or nursing for him though.

My oldest (PA/TNA) was exposed every which way. I ate tons of peanuts, reeses cups, peanut butter, tree nuts, etc while I was pregnant on the advice on my OB and every pregnancy book and article I ever read. If I knew then what I know now...

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[b]~Gale~[/b]

[This message has been edited by katjam99 (edited May 15, 2007).]

Gale,
I can relate to the "if I knew then..."
It's so painful to think that we may have had anything to do with our children's allergies.

But really, no one really knows all that adds up to having an allergic child. Its certainly more than even exposure.

FAI and others are funding a huge study in England where they are introducing peanut early (in the form of "Bamba" a peanut flavored crunchy snack--somewhat similar to a cheeto)

They are trying this on atopic kids, I believe those who are already sensitized to egg protein. Of course no one should ever, ever try anything like this at home.

They theory is that the early exposure will induce tolerance.

My point is, who knows?

Take care,
Gina