Quick question about RAST test...

Posted on: Thu, 12/20/2007 - 2:50pm
mfharris's picture
Joined: 02/21/2007 - 09:00

My ds had a RAST test this afternoon to check for a possible wheat/gluten allergy. A full food panel was done, which includes peanuts, which he has never been exposed to. I'm assuming the results won't be accurate, right?


Posted on: Fri, 12/21/2007 - 3:02am
SuziQ's picture
Joined: 12/14/2007 - 17:45

YOu dont have to have been exposed to the item to have an allergy to it. The RAST test checks the blood for the antigens(????) that are already in his system just waiting for a trigger. There is a slight chance for a flase positive or negitive (and one way is more likely then the other I just cant remember which one now) but since your younger child already has food allergy issues, and he had an older sibling that has them he is unfortunatly predisposed to having more. I would be very cautious in confronting what you may thinkg is a false postive on him.
My younger 3 have never had an exposure (that I am aware of) and they all get the CAP RAST testing due to my older son who has had reactions to PA. The younger 3 have started out quite high and as they get older the #s have come down a lot. Two have even come down to the point that the allergist was willing to do a food challenge on them but there was no real point to it. I wouldnt be feeding it to the kids anyway as I still have 2 others that are too high to test (but are coming down!!!!). And they only had a 50/50 shot at being able to pass the food challenge anyway. I would rather wait until the #s are so low (if only!!!!) that they would have say a 20/80 chance of reacting.
Talk with your allergist about the likelyhood of a false postive but be very careful he is young!! The longer you keep him from being exposed to it the more likely he will be to not react to it.


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