RAST vs. skin testing

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My 4yr. old son has peanut and egg allergies. We haven't pushed for allergy testing because our ped. doesn't feel it is necessary, and has the "just avoid all nuts and eggs" attitude (we have been VERY happy with him up to this point).

All last week my 2yr. old broke out in hives after eating meals and snacks. We thought we had it nailed down, but now when we anticipate a break out (to confirm our suspicions) - he doesn't.

Needless to say, now we are demanding testing either by him or another dr. on both boys. BUT now -- which do we do?

Supposedly, RAST isn't as accurate. But 4yr. old has eczema (and asthma) and I don't feel comfortable doing a scratch test on him. HELP!! Any suggestions?

THANK YOU!!!!!!!!!

On Feb 26, 2002

Hi there! My daughter also has eczema and asthma and we had the skin testing done on her at 3 yrs of age. They did it on her back though, which is not usually a problem area for her eczema, and were able to come out with some pretty conclusive results. Good luck! :-)

On Feb 26, 2002

Hi, My daughter, who also has eczema and asthma, had RAST testing when she was approx.12mos, and prick tests(on her arms) when she was 2&1/2. The results were quite similar, but I like the prick test, because it's done right in front of you and the results so concrete, because you see the affected area as it changes. jillsmom

On Feb 26, 2002

I would get the CAP RAST for Peanut, it is a special type of RAST test, it will tell you the likelyhood of a reaction after an exposure. eg. a score of 15 means there is a 95% chance of a reaction to an exposure -- (I think!, I don't remember, sorry, my daughter is 'off the chart' somewhere over 100 so I really don't remember how the lower scores break down.) The reason I suggest the CAP RAST for peanut (not sure if they have it for egg, it only exists for 4 allergens) is because it is QUITE accurate, unlike the regular RAST test. AND it is better than a skin tset in that you are not having to deal with and 'exposure' to the allergen. good luck! Diane BTW IF the CAP RAST comes back with a REALLY low score, so low that you think that there might not even BE an allergy, you can always 'do' a skin test. hope this helps.

On Feb 26, 2002

Thanks for all the encouraging info.

Those of you who have been through the skin testing -- was it pretty uncomfortable for your child?

I was also concerned about Drew being exposed to the peanut allergen during the skin test. Did that bring about a nasty reaction on your child?

He has only been exposed one time for maybe one second (or less) on his tongue, he spit it out, began screaming, breaking out in hives and his eyes started swelling.

I'm REALLY nervous about all this, but it helps getting info. from people who know. THANKS!!!

On Feb 26, 2002

Both of my ds's have had skin tests on their backs. They both have eczema, and my older has asthma. Both of them did fine with the skin tests. Each time, they tested about 32 sites on their backs, and each son started twitching while they had about 8 to go. We were able to talk them through to the end. Recently my older was just scratch tested to 18 more sites on his back, and 8 injections under the skin on his arm. He said the under the skin injections were the worst, but it may just have been that he could see the needle. I can't say for sure. We got pretty conclusive evidence for each boy's testing. Good luck! Kristi

On Feb 27, 2002


We've done both ways, skin was at age 3-1/2 and 6. Since then we've done the CAP RAST each year. However, this year we will have RAST testing done- which used to be done incorredtly but know is done correctly and is just about the same as CAP RAST testing.We won't do skin testing re huge welts(I guess these were large hives) that appeared at age 6 at peanut site and other places on his body. Plus it is a exposure to the allergen- several others on this site had PA have life-threatening reaction to the skin prick. Yes, they can test egg by RAST. My son has 7 things tested but had more when he had more allergies. Results were consistant between the two types of testing. Another reason I like the RAST testing is that learn which allergen are likely to be outgrown and at what levels food challenges can be done.

Once child gets over the fear of needle having blood drawn is quick and less uncomfortable than skin testing- even at 3 he was very itchy at the possitive sites and didn't feel well. I got him a game to play with each time and had reward of toy after blood work. Even now at 11 he expects 3 dollars to buy something as reward.

Take Care, Jandy

On Feb 27, 2002

Jacob has been skin tested twice. The first time his reaction was only at the test site on his back. He is allergic to peanuts and tree nuts and his welts were as about the size of an orange. His second skin test had the same results but he also experienced a literal allergic reaction to it. He started complaining of his throat itching, sneezing, coughing (also has asthma), and then diarrhea. They watched him closely and gave him Benadryl. I will NEVER allow him to be skin tested again.

On Feb 27, 2002

CAP RAST testing is avaiable for a wide variety of foods. Logan has so many allergies we do both the skin and CAP RAST tests. We first do the skin to narrow down our list and then do the CAP RAST to confirm the skin results. Most recently Logan was tested for 70 different foods. Of those, we CAP RAST tested him for the 32 that he had the largest reactions to to see if we indeed need to avoid those foods. Where the CAP RAST and the skin test are both positive we avoid.

Logan's allergist will NOT skin test him for peanuts because it is too dangerous.


P.S. Logan has asthma and eczema.

On Mar 1, 2002

My son was skin tested at 18 months for peanuts, dust mites, eggs and soy. We didn't have any problems. His peanut reaction was about the size of a nickle. I thought that was really bad at the time, but from what I heard from other people, his reaction was pretty mild. We didn't have any after effects either. The welt went down by the end of the day on its own and that was it. No other reactions. Maybe this means he is only mildly reactive to peanuts and not severe? I'm not sure. He has not been RAST tested which I am planning to ask about having done when we go to our appointment next week. He is now 4 and had eczema as an infant/toddler but seems to have outgrown it in the last year or two. No asthma (as of yet anyway).

On Mar 1, 2002


I just read your post and I am thinking the same about perhaps my Austin since his welt wasn't that big 6mm diameter on the wheal.

He had infancy eczema and grew out of it around 2? His skin is beautiful. I just am waiting for the Cap Rast results from his allergist. He had that done 4 weeks ago. The Secretary would only tell me that the results were positive but I'm hoping for a lower score since he never reacted with the size of a orange ever on the scratch tests.

I'll let you know.

[This message has been edited by smack (edited March 01, 2002).]

On Mar 1, 2002

My son is 6 and we have known about his allergy since he was one. When he was three he had skin testing done and the doctor was amazed at how bad the peanut reaction was! He also was alergic to tree nuts at the time. Anyway we brought him back to the doctor when he was five to retest him because he has not had any reaction since he was 2 and me with my wishfull thinking thought that he might of outgrown everything! Well he outgrew most of the tree nuts but still tested extremely allergic to the peanuts. He has had severe excema and asthma his whole life. Now I'm wondering if I should get a RAST test on him to know for sure. I don't know why but I've always had this feeling that he is now peanut allergic or he has outgrown it. We still are extremely carefull at school and at home of course but I can't shake this feeling. Can someone let me know more about this RAST test my doctor has never mentioned this test but he has said that Taylor will never outgrow the peanut allergy !

On Mar 1, 2002

Although Coop measured 17-19mm with the last test his welt was gone before our visit was complete and he didn't seem as bothered with the itching as the first time. The first test was done at 18 months and was tested for everthing so I had to hold him and not let him move (which was fun for an itching, scared, very active 18 month old!) It is so scary to see that welt growing so quickly just by placing some peanut on his skin!!! But it sounds like it really doesn't matter the size because this is so unpredictable. I want to know if this welt size corresponds directly with a much more severe reaction..airborne and-or contact. I hate not knowing what to expect! She basically said she didn't know! What comfort!

On Mar 1, 2002

Taylorsmom; I found this article dated May 2000. It is an interview with the V.P. of Pharmacia, the company who does the developed the rast test. It's from WebMD. If the link doesn't work, let me know, because I've copied the article and can e-mail it to you. It has info explaining the test. Beware though, it is a few pages long, but it explains a great deal.


On Mar 2, 2002

Thank you Diane for the info! I have an appointement for Taylor on March 15 to be retested and I need all the information I can get!