Blood test vs skin test

[burke-a-bee]

My DS had a blood test about a month ago and we found out he has moderate allergies to peanut, soy, wheat and egg whites. Since then we have eliminated all of those foods but have decided to see an allergist. My ped says that he will be given the skin test when we go. My question is...is the skin test more accurate than the blood test? Is it more specific? Does it hurt? Anyone here have experience. Thanks.

[burke-a-bee]

Anyone????????

[karin95]

You can't assume the allergist will do a skin prick test. That is not always necessary. Especially depending on the age of your child. The way I understand it, the blood test has a larger chance of a false negative (like 10% chance), but not very high chance of false positive. So if you're testing positive on the blood test, it's probably not wrong.
the SPT has a "higher" chance of false positive, but lower false negative.

There are reasons to do either, or both, and your allergist will let you know if the additional test is necessary. From what I've heard, the SPT doesn't hurt, but if there are reactions, it can be itchy. And you have to sit there for a long while to wait for the reactions, if any.

Your ped should know this, but the numbers that you get from the blood test do not tell you the severity of the allergy. You say your son has "moderate" allergies to various foods - that doesn't actually mean anything. The numbers just tell you if there is an allergy or not. Higher numbers indicate that there's a lower chance that it's a false positive. So if you have high numbers, then you almost definitely are allergic to x, y, z. But it doesn't mean anything about the *reaction* to those allergens.

This is a really important point, because you can feel a false sense of security if your child has low numbers. A person with low numbers is just as likely to have a severe, anaphylactic reaction to an allergen as a person with high numbers. No matter what the numbers are, you need to keep your child away from his allergens. And remember that you child may be allergic to something else that was not tested for - so be careful when introducing a new food.

[Chinese Pistache]

I agree with the pp. Both tests have their place and are tools in identifying allergies, but neither one are the end-all-be-all. The skin prick test identified my dd's two biggest (at the time) IgE allergies. We did the blood test, too, and even tested for the same allergens she tested pos to on the spt, and they came back neg. And, in fact, nothing we blood-tested for came back pos, even though she was clearly reacting to the foods we tested for (I think they are some combination of "true" IgE allergies and food sensitivities/intolerance).

In our case, the spt didn't hurt at all. Dd was pretty oblivious to it. She was annoyed at having to sit still for 10-15 minutes while we waited for the results to appear though. She was 15 mths old when we did it and I as I understand, most allergists don't want to do an spt on a baby younger than 1 yr.

[burke-a-bee]

Thanks for responding...my son was not having a skin reaction to any of the foods I mentioned. I had him tested because there were moments when his behavior ( specifically his energy level) was off the chart. The blood test came back ( I got a copy from the ped.) with a range chart and he was in the moderate range. We've decided to see an allergist because we are at a loss as to what we can feed him (oats?, chocolate?....etc.). My ped is the one who told us they would do the skin test at the allergist. Also the receptionist from the allergist office said that they would do the skin test.
Thanks again.

[shellynnrn]

My DS was 14 months and didn't really seem bothered by it. The 15 minute wait was fun tho. Take some fun toys with you!