Baffled about testing

Posted on: Wed, 07/28/2004 - 12:02pm
anonymous's picture
Joined: 05/28/2009 - 16:42

We had Andre tested for peanut allergy after he developed hives while eating food from a Chinese restaurant that did not contain peanuts (possible cross-contamination?). He tested positive to the skin prick test (a small hive smaller in diameter than an eraser at the end of a pencil). We soon became a "no nuts" household and have avoided absolutely any chance of exposure since then. At the age of 3, we had a RAST test done mainly because I was curious to see what his level was and because I wanted to monitor it as he got older. Surprise, surprise -- he tested completely negative to everything, including peanut. We continued to treat him as though he were allergic, wanting to wait until he got a bit older to test again and/or do a challenge. We figured if there was any chance he could outgrow it, what would a few more years of no nuts hurt?

Now that he's about to enter kindergarten, we decided to do another skin prick test, with the intention of going on to a challenge if it was negative. He tested positive today. The reaction took more than 10 minutes, and the hive was very small -- about a 3.

So now we're really confused. The allergist said the skin prick test is more accurate than the RAST since the RAST only detects antibodies in the blood and if he hasn't been exposed to the protein much there wouldn't be a high enough level of antibodies for the RAST test to detect. Yet I have seen posts on this board that say the RAST test is more accurate than the skin prick test.

This is so confusing! If anyone can enlighten me, I sure would appreciate it!

Many thanks!

Andre's Mom

Posted on: Thu, 07/29/2004 - 7:44am
Gwen 5's picture
Joined: 01/24/2003 - 09:00

I can imagine how confused you must be. Frankly I don't know what to believe with these tests anymore. It does sound like maybe you should have a food challenge at the allergists office or else continue as if he is allergic.
Did they test him for anything else? was it negative? It sounds like you are in a good way in the sens that you really need to be aware of what goes in his mouth but maybe not hypervigilant about if other kids eat it. Just a thought!
Has he ever had a reaction? A positive skin test is an apparent very true indicator, but I would expect his RAST to be pos. also.
Sorry not much help..

Posted on: Thu, 07/29/2004 - 8:01am
BENSMOM's picture
Joined: 05/20/2000 - 09:00

I'd get a RAST test and if it's negative, an oral challenge. Skin prick tests have an incredibly high rate of false positives, especially if the child is generally allergic to begin with (does he have environmental allergies or other allergies?) I think (but I'm not sure)that a negative on a skin prick test is quite accurate. But a positive doesn't mean much without a history of reaction or some other indication. This is what I was told by Dr. Wood--a leading pa allergist.

Posted on: Thu, 07/29/2004 - 10:31am
California Mom's picture
Joined: 07/14/2000 - 09:00

I agree with BENSMOM. It sounds like your son may be one of the lucky ones!!!
[img][/img] Miriam

Posted on: Thu, 07/29/2004 - 11:01am
anonymous's picture
Joined: 05/28/2009 - 16:42

Thank you for your responses.
The one and only reaction Andre has ever had was the one I posted about -- hives while eating Chinese food at the age of 21 months. We had him tested shortly thereafter, and when the first skin prick test was positive, we became hyper-vigilant about what he eats. So no reactions since then, but to our knowledge he's had absolutely no exposure to peanut in all this time.
When we did the RAST test, we also had him tested for all tree nuts, and he tested negative to everything. During the skin test this week, he was tested for peanut, crab, shrimp, lobster, walnuts, pecans, cashews, almonds, brazil nut and hazelnut. He tested negative to everything but peanut.
We do believe he has environmental allergies as he has had a continuous stuffy nose and itchy eyes since the Spring. He is now on Nasonex and doing very well with it. Our allergist wants to wait until he's had symptoms of environmental allergies for six months before doing any testing, so as of yet we still don't know what he's allergic to -- only that he definitely does have some environmental allergies.
The allergist didn't seem to think a peanut challenge is necessary -- he is convinced the skin test is our true answer and the RAST may have been negative because Andre just didn't have enough antibodies in his system to test positive with the blood test. It's just so confusing.
Another thing that has me wondering is whether we should insist on a CAP RAST test. Our allergist only does RAST, and when I mentioned CAP RAST he got a bit defensive and said CAP is simply a particular brand of RAST testing and it is not a better test.
Any thoughts?
Andre's Mom

Posted on: Thu, 07/29/2004 - 12:21pm
smartalyk's picture
Joined: 07/20/2004 - 09:00

I have been wondering the same thing about testing! I have heard that the CAP RAST is the most accurate but also the most expensive and most labs don't do the CAP RAST.
I too would like to know which the best and most accurate is as we have had different results on every test we have had for our son. His RAST test last fall showed him allergic to wheat and soy, which he consumed every day and never had a reaction. We cut back but did not eliminate and he still has never had a reaction to those two. He definitely has had anaphylactic reactions to peanuts, eggs, and Ibuprofen though.
It is all so confusing!
I hope you get some answers and pass them on to me too please! LOL.

Posted on: Thu, 07/29/2004 - 1:05pm
rebekahc's picture
Joined: 12/02/1999 - 09:00

I also agree with bensmom.
My first thought when you said he reacted to Chinese food was an MSG reaction - many people are sensitive to that.
Good luck and keep us posted...

Posted on: Fri, 08/06/2004 - 10:43am
anonymous's picture
Joined: 05/28/2009 - 16:42

I have the same issue with my dd. She tested positive on the skin test and negative on the Cap Rast (at least I was told it was Cap Rast and not just Rast). The allergist wants to do the challenge but I am a little concerned due to some on the information I have read on this site. However, I would like to have epi-pens for her and don't have a prescription. Her older brother is PA and has epis but we can only get two a year. Not enough. Keep us informed with your situation and any information you get on the subject.

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