How much weight do you put on Cap-RAST results????

Posted on: Sat, 08/25/2007 - 2:41am
Gwen 5's picture
Joined: 01/24/2003 - 09:00

I am wondering about your thoughts when you have your kids blood re-tested over the years how significant it is if the numbers come way down?

Do you do anything with the results as far as letting your guard down a smidge?

I know I have heard others say that their child's number went to <0.35 they do a food challenge, but are still reacting to the food!

I guess I am wondering how significant the findings are if the numbers go down and if they do, is their a next step?

I look forward to how you all feel about this.


Posted on: Sat, 08/25/2007 - 3:16am
chanda4's picture
Joined: 12/14/2006 - 09:00

I think this is so individual, it's hard to give an exact answer, because everyones answer will be different. I did retest my son's(6) peanut this summer, but the allergist said to me(quite seriously) "this isn't going to change anything, he is most likely a lifer with the severity of his allergies". That sunk in and hit hard. I will most likely back off on rast testing the next few years. I guess I was doing it every year because with *some* foods they do occasionally outgrow around the 4-5 age group(like sometimes, milk or egg etc...). But my son is now 6 1/2 and he is actually getting *more* foods popping up.
My 4yr old I will check his milk again, I am still hoping he will outgrow(his numbers are dropping and we are in the 1.0's maybe???) but he also did just pop positive for peanut and tree most likely he is a lifer there as well. I think(for me) the cut off to follow rast will be about age 6(unless new reactions show up again), after is what is it and it's probably not going to change. But that's just my opinion on things, with my kids....
edit spelling
Chanda(mother of 4)
Sidney-8 1/2(beef and chocolate, grasses, molds, weeds, guinea pig, hamster & asthma)
Jake-6 1/2(peanut, all tree nuts, seeds(all-sesame, sunflower, poppy, pine nut) beef, chicken, eggs, coconut(also avoiding legumes), trees, grasses, weeds, molds, cats, dogs, guinea pig & eczema & asthma)
Carson-4 (peanut, tree nuts, milk, soy, egg, beef and pork, cats, dog, guinea pig, hamster, grass, mold, dust mite and EE)
Savannah-1 1/2 (milk, beef and egg, dog(avoiding peanuts, tree nuts, strawberries, seeds, legumes and corn)
[This message has been edited by chanda4 (edited August 25, 2007).]

Posted on: Sat, 08/25/2007 - 3:49am
lakeswimr's picture
Joined: 02/01/2007 - 09:00

There are positive predictive values and negative predictive values for RAST test results of some food allergens. I don't have them handy right now but there are #'s that indicate from research if you are below them you have a 50/50 chance to pass a food challenge and other #s that give you almost for sure chance of passing a food challenge. Also, there are #s above which that indicate almost for sure the person may have ana if they eat the food.
What *I'm* going to do is if DS's #s fall to the point they are considered negative or low enough that he has a *good* chance to pass an oral challenge I'm going to have him do it. Some others don't ever want to add the food back in but I do. I can understand if someone had a very traumatic experience just deciding it isn't worth it and that they will avoid forever, though.
I would talk with your allergist about this.
For now, if the results are still positive a positive is a positive. I would not treat DS's allergies more lightly now even though some scores went down.
I *did* treat dairy and eggs more lightly because the scores were *very* low two years ago. Well, his egg went up last year and he also had a bad reaction (ana) to ingestion of egg. The accidental ingestion was *NOT* from taking egg and milk more lightly but I had been treatning them as if they weren't probably even real allergies based on the super low test results we had the year before. I even made the mistake of telling others about this and some other people stopped taking his egg and dairy allergies seriously as a result. So no more over thinking resuls for me. If still positive treat as seriously as before.
Good luck!

Posted on: Sat, 08/25/2007 - 4:10am
anonymous's picture
Joined: 05/28/2009 - 16:42

Just "relative" weight. I know people who have severe reactions with low numbers and mild reactions with high numbers.
Ryan has tested 2 out of 3 times with a >100 RAST. He had severe reactions around ages 2 and 3. Nothing since the age of 4.
The only thing that really pleases me about a high RAST score is dealing with schools and the fact it may open up a clinical trial for him.

Posted on: Sat, 08/25/2007 - 5:20am
booandbrimom's picture
Joined: 08/23/2000 - 09:00

I consider them for entertainment only value at this point.
My son had

Posted on: Sat, 08/25/2007 - 9:02am
falcon's picture
Joined: 07/03/2004 - 09:00

Do you avoid foods solely based on RAST results? My child has not even tried some foods, or maybe did on an occasion or two without a problem and the RAST showed positive at various levels depending on the particular food. The foods he has reacted to are positive on RAST, so I am hesitant to give him foods that he hasn't had that showed positive on a RAST. According to the RAST my son is allergic to most vegetables and fruits, most nuts, peanuts, all legumes, coconut, various pollens.
I realize that fruits and veggies can be crossreactive wtth pollen. But a reaction is a reaction so doesn't make much difference to me if a food is cross reactive with pollen. Being wary of cross reactivity has put me on guard and made it difficult for me to introduce foods that he Might be allergic too. It is so frustrating.
[This message has been edited by falcon (edited August 25, 2007).]

Posted on: Sat, 08/25/2007 - 9:07am
booandbrimom's picture
Joined: 08/23/2000 - 09:00

Falcon, that's a really hard question.
We did avoid some foods based on RAST results for at least a while. Our reasoning was that a child's immune system takes a while to "lock" and we didn't want to risk exposing our son to allergens that had potential to be serious and life-long (fish and cashews in our case).
When we was 8 or 9, we started doing challenge tests in the dr's office for things where he had a positive RAST but no actual reactions. He's gotten cleared for most everything. He failed the pea test, but he had previous reactions to peas so we knew this was a real allergy.
There are lots of people on this board who are very afraid to do challenge tests. I'm not sure how you can really know your child is allergic to something without them. To me, it's worth the couple of hours of stress to be able to cross things off the list.

Posted on: Fri, 09/07/2007 - 2:34am
Jacobs Mom's picture
Joined: 02/12/2002 - 09:00

My son's pediatric allergist actually told me that he would prescribe the CAP RAST if it would make me feel better but that it should not change our behaviors and additudes toward the allergy.
I was pretty skeptical when he said this. My reaction was -- Why shouldnt we continually test him?!?! Of course, best case scenario is that his numbers would go down! (My DS is almost 4 years old with PA)
At first I was confused about his recommendation, but after waiting for the results of the test, I came to understand it a little better. During that week or so of waiting, I was sooooo super anxious, I had my hopes up high and then when the results came (Class 6), I became so seriously sad.
Also, I dont want to provide any false hopes to DS in the future.
Not sure where I stand on future testing anymore...How have others handled? Annual testing? Bi-Annual? No testing after a certain age?
[This message has been edited by Jacobs Mom (edited September 07, 2007).]
[This message has been edited by Jacobs Mom (edited September 07, 2007).]

Posted on: Fri, 09/07/2007 - 1:38pm
MJMD's picture
Joined: 07/18/2003 - 09:00

We test annually w/a Cap Rast. Our allergist thinks it's more accurate than a Rast. Our son is P/TN, and his level of Peanut fluctuates by a little each year - sometimes up, sometimes down. It is usually >100, but this last time it was 93 (woohoo!! haha).
Something I found peculiar was that 2 summers ago, his CapRast came back positive for cashew, pistachio, hazelnut & brazil nut. I have never knowingly exposed him to these, (except while them!). We also met 2 other boys who suddenly "became" allergic to tree nuts at age 5-6 like our son, and they had no history of food allergies. I thought it seemed odd. Really farfetched, but maybe a pre-kindergarten vaccination???
His tree nut levels are all very low (.37, 1.65, etc), and they remained about the same this past summer when we retested, which I was happy about (plus he hadn't added any extras). So the CapRast seems to be pretty accurate for us, and consistent in its findings.
Oh, and our allergist will only use Quest labs vs. Labcorp.

Posted on: Sat, 09/08/2007 - 12:10am
Carefulmom's picture
Joined: 01/03/2002 - 09:00

Our allergist also will not do a rast, only a cap rast. He only uses one lab which is IBT in Kansas. Dd`s scores have been dropping ever since the age of 10. She`s 12 now and her peanut cap rast is about 1/3 of what it was at age 9. Her milk, though, is unchanged. Interesting comment from Ryan`s Mom about the clinical trials. When dd was much younger her peanut cap rast was high enough that her allergist asked me if I wanted to put her in a clinical trial. Don`t recall if it was Xolair or Tanox (since they are both basically the same thing--anti IgE). Anyhow, I said no, because the person has to have a peanut challenge before and after the treatment/placebo to see if they can tolerate more peanut after. I could never go along with that even though the challenge is very carefully controlled and in a hospital.

Posted on: Sat, 09/08/2007 - 8:39am
SFMom's picture
Joined: 11/27/2006 - 09:00

What is the difference between a RAST and a CAP RAST? I looked it up but couldn't find enough info.
Our allergist only wants to do skin prick testing. He says that the blood tests are not reliable enough. I've had my kids (ages 13 and 11) tested only twice in their lives. I'm thinking about having new tests done next year, now that my oldest daughter has gotten her see if the hormonal changes in any way have affected her food allergies.
I would obviously love to get a blood test intead of a skin prick test. Until I came on this message board, I didn't realize that skin prick is actually an exposure. Makes me wish I hadn't had the skin pricks done twice before.
[This message has been edited by SFMom (edited September 08, 2007).]
[This message has been edited by SFMom (edited September 08, 2007).]


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