Negative skin prick, positive RAST

[staceyshoe]

We went for my 2 y.o. ds's annual allergy check up a couple of weeks ago. His skin prick came back positive for a few things which were not a surprise. It came back negative for several things including wheat. I explained to the dr that ds does not tolerate any form of bread product so he requested testing for celiac and a RAST for wheat. The RAST for wheat came back positive.

When ds was diagnosed with allergies last year, I think I read that the skin prick is a more sensitive test for detecting classic IgE allergies. Is it unusual to get a neg skin test and positive RAST?? Now I'm doubting all his skin prick results since we didn't get the RAST to back up the other negatives. Am I worrying unnecessarily?

[changingseasons]

Both tests can have false positives and negatives.

Did they retest the wheat SPT? The office we use has these holders that have 6 tests on them, and they press the whole thing into your back at once. Every single time we do them, I tell the nurse that the center ones didn't hit the skin enough (because DD's back was slightly bent or something) and they always end up having to redo some of them. Or even with the single pricks, sometimes they do it really quick and it doesn't penetrate the skin enough.

I think either way, if you've seen a reaction and you get a positive on EITHER test, you have a positive.

[staceyshoe]

Thanks for the reply! They didn't re-do the SPT. The nurse just called me with the results of his RAST. It may be that he was wiggling around too much during the SPT. Next year I think I'll have him do both the SPT and RAST for everything he wants to test. Ds has multiple allergies but his primary symptom is stomach pain. It's sometimes hard to figure out if he's just clingy (which he tends to be) or if he's having an allergic reaction. As unpleasant as rashes are, it would be so much easier to be able to look and see that he's reacting to something. I watch for reactions in him, but I'm also relying a lot on test results instead of assuming that I would "see" the problem if there is one.