Real life vs. RAST/skin tests


I've been looking at many of the posts and searching old threads, but still have a question. What are your experiences with what a skin test/RAST show vice what you see in your child? I'm asking this because we are going to our first allergist appointment in a few weeks and I want to have some (second hand) working knowlege of what tests he might get. My dd has had significant eczema since birth, so I am pretty certain it is a food allergy, but I've been unable to pinpoint it. I'm hoping he will be able to test her and point us in the right direction. I've seen in many posts though that levels on RAST testing and skin testing did not seem to correlate with actual experience. - I'm not talking about PA here, as I know that any exposure, any test level, is significant. - but I'd like to know if eliminating the dogs and soy for example would give her some respite. The poor baby looks horrid from her scratching - and that is with Zyrtec, steroid cream, hypo-allergenic detergent and soap.

So I guess my question is can I expect that the allergist will be able to tell me about her other probable allergies and if so can I use the results?

------------------ Lori Jo,

Rose, 7-31-02, PA Beatrice & Georgia, 8-14-99

On Oct 13, 2003

My ds also had eczema. Skin testing revealed his peanut, treenut and egg allergy. It did not reveal his soy, dairy, or wheat allergy. RAST testing revealed these three, plus barley. He's subsequently had reactions to foods that tested negative on both tests, but these reactions have been GI based so would probably be categorized as 'intolerances'.

The testing may help you as a guide, but the true 'test' is whether or not the child reacts.

On Oct 13, 2003

I think that the skin testing is pretty reliable for environmental allergies. It's the food allergies where you run into false positives and false negatives. Sometimes an elimination diet can help to dertermine the allergy if the tests are unreliable.

On Oct 13, 2003

When I was a baby (maybe age 2), I was skin tested for foods and environmental allergens. I came up positive to almost everything. I was put on a VERY restrictive elimination diet for 4 years. Basically I lived on chicken, potatoes, rice, and some fruits and vegies. I do not know if I was truly allergic to all the foods I avoided but I do know that my eczema and asthma improved. As far as environmental, the skin tests are usually fairly accurate. Rast testing was not around when I was newly diagnosed. However, 3 years ago I had CAP Rast to peanut, tree nuts, mango, beef, soy, eggs, and dairy. My peanut and tree nut was class 3 and 5, respectively. Mango was 0. Soy, beef, and eggs were a 2 and dairy was a 1. I was food challenged to mango, soy, beef, eggs, and dairy and passed with no problems.


On Oct 14, 2003

Ryan had severe facial eczema when he was a baby/toddler.

His peanut skin and RAST (first >100, second 64) tests correlate well with past reactions. A definite peanut allergy.

His tree nuts (had him tested for almonds, walnuts, pecans, and cashews) is ambiguous. His numbers are very low compared to peanut (ranging from .99 - 1.54, with pecans borderline negative), however there were no reactions to these before we elmininated them when we found out about his PA. He consumed these a lot in cereals and baked goods, with cashews being eaten for lunch virtually every day between the age of 2 1/2 and 3. Cashews produced the highest tree nut positive at 1.54. I guess he's already been "food challenged" but we avoid them anyway right now.