Test results!!!

Posted on: Wed, 09/13/2006 - 11:34am
madjax's picture
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Joined: 09/13/2006 - 09:00

Hi there... Can anyone tell me what a high blood test result is?? My DS is PA and had a blood test done...they told me that normal os 0.34 and he tested 21...Duhhhh but what does that mean??
Thanks so much!!

Posted on: Wed, 09/13/2006 - 1:16pm
Corvallis Mom's picture
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Joined: 05/22/2001 - 09:00

Welcome!
I think the reason that you aren't getting much response is that without knowing a bit more about what kind of "blood test" this was, it is impossible to say what it might mean.
I think this probably (given the lower number you were quoted) is an ImmunoCAP RAST result. This test measures the amount of allergen-specific IgE (that is, the immune modulator that can bind a particular allergenic protein) within a blood sample. This test has a normal linear range of 0 to 100 kU/l of blood. Anything over 100 is out of the linear range of the test.
What it "means" is a horse of another color, however. [img]http://uumor.pair.com/nutalle2/peanutallergy/wink.gif[/img] The higher the number, the more likely a person is to be "clinically allergic" to that substance. At some point, the number is pretty much 100% predictive of a "real" allergy. For peanut, you are almost certainly past it. In my recollection, that 95% predictive value is less than 5...
But it means NOTHING about how sensitive the person is (ie-- do they have to actually EAT pn to have a rxn, will they have an asthma attack in a room with someone eating pb, etc.) OR how severe the next reaction will be. People with RAST numbers of 0.00 have had anaphylactic reactions requiring hospitalization.
Prior reactions being mild are [i]no assurance[/i] that the next one will be similar.
So most of us here feel that "allergic is allergic."
Does this answer some of your questions?
ETA: Just to give you some way to compare, my daughter's initial RAST at 11 mo (after a near fatal anaphylaxis episode) was about 20 as well. It has since spiked up to over 100 where it has stayed for many years, evidently regardless of how little exposure she has. She is unfortunately also very sensitive to touch and inhalation, which gradually became evident about two years after her initial diagnosis.
[This message has been edited by Corvallis Mom (edited September 13, 2006).]

Posted on: Wed, 09/13/2006 - 11:12pm
anonymous's picture
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Joined: 05/28/2009 - 16:42

I thought is someone had a rast of 0.00 that they were no longer allergic???

Posted on: Thu, 09/14/2006 - 12:54am
LisaM's picture
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Joined: 11/04/2005 - 09:00

Not necessarily---from what I've heard allergists will recommend an oral challenge to confirm that the child has grown out of the allergy. It is possible to have a negative RAST and to have an allergy. It is also possible to have a positive RAST and not to have a reaction . . . for this reason, a lot of doctors view the skin prick tests as more reliable and use the RAST for a confirmation if the diagnosis is questionable. (Although the spt isn't necessarily 100% reliable either. An allergist once told me not to eat foods to which I had a negative skin prick test which I have never had before (we were talking seafood here--I have a positive spt to some shellfish and some fish) . . . if I wanted to try them, I'd have to do so in his office.

Posted on: Thu, 09/14/2006 - 2:24am
3xy1PAinNH's picture
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Joined: 08/07/2006 - 09:00

Quote:Originally posted by Corvallis Mom:
[b]
The higher the number, the more likely a person is to be "clinically allergic" to that substance. At some point, the number is pretty much 100% predictive of a "real" allergy. For peanut, you are almost certainly past it. In my recollection, that 95% predictive value is less than 5...
][/b]
I was just researching this, and I believe the 95% predictive value is actually 15, not 5.
Having said that...Corvallis mom...I must tell you, you do an excellent job of getting out exactly the right details and explaining it in an excellent manner. I have learned well from you in just a couple of weeks! Thanks for the great explanation!

Posted on: Thu, 09/14/2006 - 4:58am
Corvallis Mom's picture
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Joined: 05/22/2001 - 09:00

Thanks for the correct info!!
(In any case, 21 kU/l is over that too!)
[img]http://uumor.pair.com/nutalle2/peanutallergy/wink.gif[/img]

Posted on: Wed, 09/13/2006 - 1:16pm
Corvallis Mom's picture
Offline
Joined: 05/22/2001 - 09:00

Welcome!
I think the reason that you aren't getting much response is that without knowing a bit more about what kind of "blood test" this was, it is impossible to say what it might mean.
I think this probably (given the lower number you were quoted) is an ImmunoCAP RAST result. This test measures the amount of allergen-specific IgE (that is, the immune modulator that can bind a particular allergenic protein) within a blood sample. This test has a normal linear range of 0 to 100 kU/l of blood. Anything over 100 is out of the linear range of the test.
What it "means" is a horse of another color, however. [img]http://uumor.pair.com/nutalle2/peanutallergy/wink.gif[/img] The higher the number, the more likely a person is to be "clinically allergic" to that substance. At some point, the number is pretty much 100% predictive of a "real" allergy. For peanut, you are almost certainly past it. In my recollection, that 95% predictive value is less than 5...
But it means NOTHING about how sensitive the person is (ie-- do they have to actually EAT pn to have a rxn, will they have an asthma attack in a room with someone eating pb, etc.) OR how severe the next reaction will be. People with RAST numbers of 0.00 have had anaphylactic reactions requiring hospitalization.
Prior reactions being mild are [i]no assurance[/i] that the next one will be similar.
So most of us here feel that "allergic is allergic."
Does this answer some of your questions?
ETA: Just to give you some way to compare, my daughter's initial RAST at 11 mo (after a near fatal anaphylaxis episode) was about 20 as well. It has since spiked up to over 100 where it has stayed for many years, evidently regardless of how little exposure she has. She is unfortunately also very sensitive to touch and inhalation, which gradually became evident about two years after her initial diagnosis.
[This message has been edited by Corvallis Mom (edited September 13, 2006).]

Posted on: Wed, 09/13/2006 - 11:12pm
anonymous's picture
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Joined: 05/28/2009 - 16:42

I thought is someone had a rast of 0.00 that they were no longer allergic???

Posted on: Thu, 09/14/2006 - 12:54am
LisaM's picture
Offline
Joined: 11/04/2005 - 09:00

Not necessarily---from what I've heard allergists will recommend an oral challenge to confirm that the child has grown out of the allergy. It is possible to have a negative RAST and to have an allergy. It is also possible to have a positive RAST and not to have a reaction . . . for this reason, a lot of doctors view the skin prick tests as more reliable and use the RAST for a confirmation if the diagnosis is questionable. (Although the spt isn't necessarily 100% reliable either. An allergist once told me not to eat foods to which I had a negative skin prick test which I have never had before (we were talking seafood here--I have a positive spt to some shellfish and some fish) . . . if I wanted to try them, I'd have to do so in his office.

Posted on: Thu, 09/14/2006 - 2:24am
3xy1PAinNH's picture
Offline
Joined: 08/07/2006 - 09:00

Quote:Originally posted by Corvallis Mom:
[b]
The higher the number, the more likely a person is to be "clinically allergic" to that substance. At some point, the number is pretty much 100% predictive of a "real" allergy. For peanut, you are almost certainly past it. In my recollection, that 95% predictive value is less than 5...
][/b]
I was just researching this, and I believe the 95% predictive value is actually 15, not 5.
Having said that...Corvallis mom...I must tell you, you do an excellent job of getting out exactly the right details and explaining it in an excellent manner. I have learned well from you in just a couple of weeks! Thanks for the great explanation!

Posted on: Thu, 09/14/2006 - 4:58am
Corvallis Mom's picture
Offline
Joined: 05/22/2001 - 09:00

Thanks for the correct info!!
(In any case, 21 kU/l is over that too!)
[img]http://uumor.pair.com/nutalle2/peanutallergy/wink.gif[/img]

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