Wednesday, February 13, 2008

Preparing for the RAST Test

For the last two years, Bella has had a Skin Prick Test (SPT) instead of a blood test to determine her food allergies.

The first year, she was allergic to peanuts, almonds, and walnuts.

Last year, she was allergic to just peanuts. Whew, no tree nut allergies! Of course, we haven't challenged the tree nuts with an oral challenge in the doctors office, so we're still avoiding them.

So that brings us to this year. Next month, Bella will go in for a RAST (also called the CAP-RAST) test. What exactly is that? I thought you'd never ask! Here's a brief statement from the NIH:
The RAST (Radioallergosorbent test) is a laboratory test performed on blood. It tests for the amount of specific IgE antibodies in the blood which are present if there is a "true" allergic reaction.
So basically (I'm not a doctor here), they take your blood and in a lab mix it with allergens to see if your blood reacts. Here's another link to an extensive overview of the RAST test.

Is it "better" than a Skin Prick Test? Not necessarily. As I understand it, both are good indicators of allergy, but for some folks the skin test isn't preferred due to eczema, medication interference, and the risk of exposure to the allergen. But our allergist, who's on the faculty at Stanford Medical School, wants to do it to see the levels in her blood as they react to Peanut. According to the AAAAI, the level of the CAP-RAST test may help predict future food allergy reactions to these foods. I've read lots of differing experiences with this, so I'm on the fence about how much faith to put in the results.

The RAST is very new territory for me, and I'm trying my hardest to understand it, and why it's necessary. But I feel that I should do it - that it's my responsibility as a parent to know just HOW allergic she is. Not that it will make a bit of difference in our diligence in avoiding nuts.

Did any of you decide not to do a RAST even if your doctor ordered one and just stay with a SPT? I'd love to hear from you either in the comments or via email.

And I must admit, I'm VERY nervous about her getting her blood drawn. I've been a blood donor for years, so needles don't bug me, but how do I explain to her that she's getting an 'owie' on purpose? I hope I don't break down in tears in the lab! I'm not sure I want to just surprise her with a blood draw without any notice - it seems a little harsh to me. On the other hand, I don't want her worrying about something that will only take a few minutes and will hopefully be fairly painless for her.

So how I am going to restrain my feisty (and strong) 3 year old? How can I help her in this situation? Bribing with a trip to ToysRUs will definitely happen, that's for sure. But do you all have any other ideas? I'd love to hear them.


allergicmom said...

I can't bear to do it, so my husband takes our son in to get the RAST blood test annually.

He reports that my son is actually quite fascinated by the process, and not squeamish at all. He's due for his next blood draw in a couple of months, and we'll see if anything has changed. He's done it twice so far, and he's just turning 5, so he was 3 the first time.

Oh, and he does get a lollipop before the procedure begins, to help distract him a little bit.

Pez said...

Ask your allergist for "magic cream" that numbs the area so the kids cannot feel anything when their blood is drawn. It is a little uncomfortable until it is numb because they apply it then wrap the kids's arm in saran wrap (at least they do here). Takes about 20 minutes to numb - just long enough to drive to the lab since they do not draw blood at the doctor's office.

One thing about the RAST is that it does not predict the severity of the reaction. DS is a Class 6 (the highest) to peanut (started at Class 4 and just kept going up-up-up). So, while we know he is highly allergic and will have a very fast reaction, we don't know if it will mean hives or anaphylaxis. DS is nearly 10 years old and his last SPT for peanuts was when he was 4.5 yrs because his whole back became covered in hives. The nurse started freaking out and that ended our hopes of 1) him ever outgrowing his peanut allergy and 2) any further SPT testing for peanuts since even an SPT is an "exposure" to the allergen.

Sorry for the long-winded reply! Best wishes with Bella's RAST test/blood draw.

Anonymous said...

My son (2 1/2yrs) had his first rast test last August. I was very worried how the draw would go but he was a real trooper. He was more scared about being held still then of the needle. All he did was say ouchy and then just sat there and watched.
My advice would be not to dwell on what is about to happen. Let her play why you wait then simple put her on the table and let the nurses do there thing. Of course she will probably cry but it will be over soon. When their done give her lots of hugs and kisses then go get her favorite lunch.
I think if you show anxiety about it, then she will remember that it is a scary and stressful thing.
Just tell her what a big girl she was and then go have a fun lunch or play at the park.

ChupieandJ'smama said...

We had SPT for our first test at 10 months of age and then do the RAST every year after that. He'll get another this May and it will his 4th (they did one at 10 months too and that one was the absolute worst!!). He sits on my lap and I help hold his arm. I also tuck his feet between my knees in case he kicks but last year was the first year he was a total trooper and didn't cry or scream or kick or anything. Maybe it helped that I bribed him with a trip to the allergy friendly candy store whioh was down the street. I told him if he behaved, he could pick out anything he wanted. It was worth it. The RAST numbers are a nice indicator if the child may be outgrowing their allery, but for us anyway it didn't predict what type of reaction he would have. Now we know he's anaphylactic to wheat by his first reaction and his last RAST numbers were over 100 (6) so I would bet that is still true. But a few years ago he was a (2) for egg and the Dr. thought it was a false positive and we challenged it and that one was borderline anaphylactic too. Number don't always tell the whole story so I try not to get too hung up on them. Just some food for thought.

Allergicmother said...

I would get blood testing done and ask the doctor for a tube of Emla cream to numb the injection site. Assuming your saughter can use it, it is a Godsend for blood draws.

Anonymous said...

Kids are incredibly resiliant. As parents, sometimes we don't give them enough credit for how tough they are capable of being. My 2yr old had his SPT and Rast tests done on the same day. He laughed with the SPT and didn't budge with the blood draw. The phlebotomists will help hold your daughter's arm so you can concentrate on kisses and telling her what a big girl she is. Hang in there, the ouches are worse for us than them sometimes. Good Luck!

Anonymous said...

Wow, I am an adult with severe allergies, and I really prefer the RAST test. I'm pretty reactive, so the SPT is a lot more painful and scary (griding up your entire back and waiting in agony while all the hives form vs just a blood draw). I also grew up with severe allergies and I got used to the needles early. I don't remember ever being afraid. I really doubt this will be a problem for your daughter unless you treat it like something you expect her to be afraid of. Remember the itching and pain of the SPT are "owies" too. If she learns to deal with this and be brave now, it will be much easier for her to manage her condition as an adult.