How can the RAST be negative and the SKIN test positive?

Posted on: Sun, 06/13/2004 - 1:47am
elliott992's picture
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Joined: 06/12/2004 - 09:00

Skin test showed off the charts allergic to peanut but rast was negative

Posted on: Sun, 06/13/2004 - 10:10am
BENSMOM's picture
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Joined: 05/20/2000 - 09:00

I'd probably get both tests done again. Skin tests have a high false positive rate, especially in people who have lots of allergies. I'd be hopeful that the RAST test is correct.

Posted on: Sun, 06/13/2004 - 10:59am
dgood's picture
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Joined: 03/27/2004 - 09:00

My 14m old's RAST test was positive for peanut and negative to all tree nuts. When she had skin testing a month later, peanut was still postitive and she tested positive for walnut too! I also wondered how this could be and wondered which test is more reliable.

Posted on: Mon, 06/14/2004 - 12:44am
samirosenjacken's picture
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Joined: 09/30/2002 - 09:00

A friend of mine had a positive food challenge to milk.. followed by a neg RAST test.. which was followed by another food challenge which sent her DD to the ER with anaphylaxis... she later found out that a RAST done by a finger stick prick may screw up the results! She is going to have it re done...

Posted on: Mon, 06/14/2004 - 3:32am
Naer74's picture
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Joined: 11/03/2003 - 09:00

My son had a negative RAST and positive skin test to peanut. However, he reacted to the food challenge and had another reaction since that time. Interestingly, his last skin test showed negative to cashews (positive on the RAST) and he also reacted anaphylactically to those.
Simply - I just don't trust ANY tests.

Posted on: Mon, 06/14/2004 - 4:53am
elliott992's picture
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Joined: 06/12/2004 - 09:00

I agree on the tests. All we know with our PA son is that since the diagnosis in december he has had not even a trace of peanut , and has had zero reactions. So better safe than sorry. The tests arent fullproof and if any medical science is still a work in progress it is allergies.

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