Skin testing vs blood testing???

Posted on: Fri, 06/20/2003 - 5:52am
Gwen 5's picture
Joined: 01/24/2003 - 09:00

Can anyone tell me which test is most reliable and is the most acurrate? I am really torn as to which test my daughter should get.

Also, is it true that testing before age 3 is not really reliable?

Thanks for all your input


Posted on: Fri, 06/20/2003 - 7:24am
SpudBerry's picture
Joined: 07/23/2002 - 09:00

All I know is that our allergist wanted to do skin testing. I said no - I didn't want to expose him to any peanut. He acted like I was over-reacting. Then when the RAST tests came back so high - he recommended that I never have him skin tested. He then claimed that this was the last year he would of recommended the skin tests anyway (3 years old) that he thought the blood tests were too traumatic for 3 year olds or younger. But my guys have never been scared of needles - don't cry for shots or such. So I guess it's what ever you or your children are comfortable with.
I don't know about reliability of one versus the other.
Mom to 3 year old twins Ben & Mike - one PA & the other not.
Stay Informed And Peanut Free!

Posted on: Fri, 06/20/2003 - 8:44am
anonymous's picture
Joined: 05/28/2009 - 16:42

Hi Gwen.
Based upon what I have learned from my daughter's allergist, I would definitely NOT give your 2 1/2 year old a skin test for several reasons:
(1) Children whose older sibling has a food allergy to avoid delay the introduction of ALL major allergens as follows:
wheat/soy/milk - 12 months
egg- 18 months
peanuts, tree nuts, fish and shellfish - 3-4 years
My DD's allergist says that if you follow this protocol (including avoidance of may contains), your child's chances of being allergy-free are very good.
It stands to reason then that if you give your child a skin test, this would count as an exposure -- and could possibly make him/her more likely to become allergic.
(2) There is a relatively high false positive rate associated with skin tests. CAP-RAST are the most reliable (next to the oral food challenge itself).
(3) I asked my daughter's allergist specifically if he could test my 2 year old sooner. I, too, wanted the peace of mind of knowing whether she would be allergic before starting preschool. He said there is simply no way you can test a child before 3 to know this with any certainty.
I would definitely question your allergist about this further. I think there's a lot of ignorance out there, even among so-called "board certified specialists" and we, as the parents, really need to make sure we educate ourselves instead of blindly trusting the doctors to make potentially life-altering decisions for us and our children.
Good luck.
[This message has been edited by Kami's Mom (edited June 25, 2003).]

Posted on: Fri, 06/20/2003 - 5:44pm
Gwen 5's picture
Joined: 01/24/2003 - 09:00

Hi Kami's Mom,
Thanks so much for your mdetailed message- I am really going to re-think this and am probably not going to have her skin tested.
She will be 3 in October- should I do the Cap-Rast test at this time?? Is this just the blood test??

Posted on: Sat, 06/21/2003 - 7:33am
virginia mom's picture
Joined: 03/12/2003 - 09:00

I first had my daughter skin tested at 2 years, then at 4 and 5 1/2. Each time, the reaction was bigger than the last time. My allergist said that he will not test her again - that each time counted as an "exposure" and that each subsequent test may have contributed to her bigger reaction - I wonder if he knew this when she was 2 - I get the impression that our doctors are learning as they go along just as we are.

Posted on: Sat, 06/21/2003 - 8:19am
anonymous's picture
Joined: 05/28/2009 - 16:42

You're welcome Gwen. The CAP-RAST is a blood test that measures the level of IgE antibody for a specific allergen in the blood. If you get it done, the lab can test for numerous allergens with just one blood sample.
However, be sure not to confuse the CAP-RAST test with the RAST test (also a blood test). The CAP-RAST is the preferred, newer version.
I won't be testing my younger daughter until May 2004, soon after she turns 3.

Posted on: Sat, 06/21/2003 - 1:39pm
pgrubbs's picture
Joined: 10/27/2003 - 09:00

My daughter was skin tested (that's when I found out her allergy info), but should I request to get the CAP RAST? What more info would it give me; would it tell me how allergic she is (other than 4++)? What else will it do? How much blood do you need?
New to this!thanks!

Posted on: Sat, 06/21/2003 - 10:06pm
reader's picture
Joined: 11/04/2002 - 09:00

Our allergist recommended at Cap Rast at 18 months. It came back as negative yet she had full body hives with an exposure to peanut butter. I would agree that testing before age 3 doesn't do any good. We are going to have her tested again when she reaches 3.

Posted on: Mon, 06/23/2003 - 12:02am
MeCash's picture
Joined: 04/18/2001 - 09:00

My daughter had a reaction to peanuts at 20 months old. Actually, she also reacted to peanut oil in sunscreen at 8 months old. I had her skin tested at age 2 and she was 4++. The only reason we did the skin test was to confirm what we already knew (my son is also PA) and get an EpiPen, Jr. The allergist said that she doesn't think a CAP RAST is necessary at this time, and that when she is over 3, we can do further testing for other potential allergens and possibly the CAP RAST for peanuts at that time.
I take this to mean that she doesn't think the testing before 3 is reliable, but she did not say as much. That was just my take on it, but regardless, I know my DD is PA as she has reacted.
[This message has been edited by MeCash (edited June 23, 2003).]

Posted on: Mon, 06/23/2003 - 5:21am
anonymous's picture
Joined: 05/28/2009 - 16:42

Just want to clarify something: I believe that Gwen's original question concerned testing her NOT-YET-ALLERGIC younger child -- one that has never had a known reaction -- to see if she is allergic.
My response to her about the futility of testing those younger than 3 was referring only to children who have never had a reaction and had never been exposed to the particular allergen being tested.
I don't think it would be correct to assume that this would apply to children younger than three who are being tested for an obvious reaction.

Posted on: Mon, 06/23/2003 - 9:50pm
samirosenjacken's picture
Joined: 09/30/2002 - 09:00

I have to ask you if the CAP RAST is more preferred why did Dr. Wood do a RAST on my daughter who is severely PA and suggest doing a RAST for tree nuts on my other DD also severely pa?
I have been told by 2 allergists the RAST is preferred.... that the CAP RAST is for those unclear results.


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