YAY!!! Low #\'s on the RAST!

Posted on: Sun, 05/25/2008 - 12:12am
MommyOfTwo's picture
Joined: 11/08/2007 - 09:44

We got my DS's RAST numbers back and they were only .40!!! Just BARELY over the positive cutoff. I'm SO EXCITED! I do have a question though...since on his SPT he got really large wheals (9mm on the first and 10.5mm on the second), if his numbers next year fall below the .35 mark and they do another SPT and he still has a really large wheal for that, they will still consider him positive?

To the best of my knowledge he has NEVER had any exposure to pn except what he would have gotten in the womb. Might that explain why his RAST numbers are so low since he has never had and outer-womb exposure but his skin reacts so much during the SPT? The low RAST numbers are really giving me hope that this is something he will grow out of, but I don't want to get my hopes up too much because he still has such a reaction on the SPT. Thoughts?

Posted on: Sun, 05/25/2008 - 4:05am
GinaC's picture
Joined: 11/11/2006 - 09:00

I'm not a doctor but I believe that in general, most would agree that lower numbers are "better" than higher ones. The experts are studying so much about allergies and can predict with some certainty who is more likely to outgrow.
Having said that, even low numbers are considered positive with peanut, a notoriously potent allergen. And you can read the abstract and blog post below to see (in at least one study) that more than a quarter of those with a negative result will still react to peanut upon challenge! And your son surely has a positive skin test.
[url="http://www.allergymoms.com/modules/wordpress/index.php?p=532"]IgE levels and test results[/url]
If I were you, I'd be prepared and cautious but remain hopeful!
Take care,

Posted on: Sun, 05/25/2008 - 5:58am
LaurensMom's picture
Joined: 05/23/2001 - 09:00

I'm excited for you too! I have heard too that low RAST numbers make you likely to fall into the category for outgrowing the allergy. I wish you and DS all the best. Congratulations!
I hope you don't mind me adding this caution. I do so not to burst your excitement but to warn you. DD had high RAST results - in the "won't outgrow" category. We tried an alternative therapy treatment then had her tested again about a year later. DD's results came back similar to your son's, although a lower - in the "insignificant" category. I was so excited too. They were considering her NOT allergic.
Then, concerned about how I would deal with this - is she or isn't she, I cornered this allergist who ordered the test.
I told him I wanted the test repeated just to be sure. He went so far as to send it to a different lab.
Unfortunately, the results came back positive - as positive as they'd ever been (not worse - just same as usual).
His "excuse" was: "All labs do not calibrate their equipment in the same manner. A 12 at one lab might be a high score while at another it might be a low score." I was furious - ranted and raved about how dangerousness of the report.
But, have hope. DD also has asthma. He treated her but things he was saying just didn't sit right with us - can't even say it was a red-flag...things just didn't sit right. He made generalizations about her non-food allergies that we just didn't like. We changed allergists - went straight to an allergist at Mass General in Boston (with whom we were absolutely thrilled!) Silly me should have asked this "calibration" question to this doctor but it never came up.
Point is, you might want to talk to your allergist (or two if you can get a 2nd opinion) to see if this labs do calibrate equipment differently. Sounds hokey, I know, (and I almost feel funny mentioning it) but I know the peanut test was ordered - can't explain why it was negative.

Posted on: Mon, 05/26/2008 - 12:55am
SkyMom's picture
Joined: 10/27/2001 - 09:00

MommyofTwo, that's great news! I hope that this is suggesting good things to come. Its so exciting to have any indication that there's a chance to outgrow. I think we all know that there are still risks until its officially tested/challenged as outgrown.

Posted on: Sun, 06/01/2008 - 2:55am
pfmom2's picture
Joined: 01/22/2006 - 09:00

Congrats on the low #s, but proceed with caution about it. Why are the SPT's big? I have a nephew who's blood came up negative to something previously anaphylactic to. They did a food challenge and he failed.
So, be hopeful, but cautious. You'll know what is right for your child.

Posted on: Sun, 06/01/2008 - 11:06am
Krusty Krab's picture
Joined: 04/20/2007 - 09:00

It [i]sounds[/i] better than high #'s, but people with low RAST #'s most certainly do react violently to an allergen. Combined with the fact that the SPT is still very large, I wouldn't allow myself to feel all that great about a low rast number. But that's how [i]I[/i] would feel.
BTW, why are they SPTing your son? Did they SPT at the same time they did a RAST? They already know he's allergic. I always consider SPT another exposure. [i]Something to avoid.[/i] Only after a negative RAST would I allow anyone to SPT my child with a known allergen. Again, this is[i] my[/i] opinion.
I hope in your case, it means good things are to come.

Posted on: Sun, 06/01/2008 - 11:58pm
MommyOfTwo's picture
Joined: 11/08/2007 - 09:44

[i]BTW, why are they SPTing your son? Did they SPT at the same time they did a RAST? [/i]
His allergist thinks SPT are more "sensitive" and a better indicator than the blood test. It think also because DS's first SPT was at 3 months that perhaps there was a chance that maybe it was a false positive(wishful thinking more than anything). I certainly will NOT be doing anymore SPT again. He only did the RAST this time around because it was his second positive SPT and the wheal the second time was even larger than the 1st time and I said I wanted to do the RAST from now on to follow his numbers.
My next hurdle is going to be dealing with military drs (allergist) when we get to our next post. I have had to fight with most of DS's drs. just to get him tested because they seem to think allergy testing is a waste of time for children under 3 years old. I'm really hoping that the allergist at our next post don't see it that way and take it seriously. No more SPT until his numbers fall below .35 and I'm hoping and praying that next year's RAST the numbers do indeed go down.

Posted on: Mon, 06/02/2008 - 2:20am
TwinsMommy's picture
Joined: 03/17/2008 - 12:57

I thought I had read that if the child has not yet been exposed to the allergen, they could test low or negative when in fact thats not the case. I'm not sure how much faith I have with the Rast. My son tested positive...low...but still positive and his reactions were very severe. Where as he tested negative to egg...yet he has a pretty severe reaction when eating eggs.
We are going to the allergist tomorrow because he has so many skin issues, I think there is more to his allergy then peanut and egg (which we of course avoid now)
I know I was super happy when I heard the word "low" come out of the peds mouth...now I don't know how much to trust the Rast given our experience.
Sorry I don't mean to burst your bubble. It's still great news...like you said...better chance of growing out!!!!

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