Re: RAST question

[Guest guest]

YES!

Not all doctors offices have the RAST test that is able to

differentiate unbound IgE from Xolair bound IgE - that's #1.

#2 and #3, I've always been told not to take an antihistamine for 48

hours prior to ANY allergy testing AND I've heard that prednisone can

also cause falsly lowered or negative scores, although my doc and I

have never had THAT particular discussion.

Talk to your doc about your scores and the fact that you did not

withhold medication prior to the test.

Addy

Group co-owner

--- In , " meagainbenny " <bennetme@...>

wrote:

>

> Hello All,

>

> This is probably a 'duh' question, and I think I already know

> the answer, but I'm not compltely sure (I haven't had a RAST test

in

> almost 4 years). Would having Xolair the day before, taking 10mg of

> Zyrtec & 7mg of Prednisone (I've been on it for 3+ years) 2-3hrs

> before RAST bloodwork cause false negative results? I am just so

> baffled by the results because I reacted to a Banana (in the skin)

I

> broke out in hives, had to take 50mg of Atarax (it was interesting)

> and my allergist decided to run a 'Latex Panel' RAST because

bananas

> apparently cross-react with latex. I got the RAST results yesterday

> (in a phone-call from a secretary, so I couldn't really ask her),

the

> panel tested for bananas too, and I tested negative for bananas.

> Which is quite odd, and my mom was like " Well, that's a good

thing, "

> but I don't think it is because at least if the banana test was

> positive, I would know to avoid bananas, but now I don't know what

> I'm allergic to. I have an appointment with my allergist in two

> weeks, and I'll ask him then, but I was just wondering if anyone

here

> might know.

>

> Thanks,

> Meagan

>

[Guest guest]

Ok, I will contradict what the other poster said about what meds can and cannot

effect a

RAST test. Antihistamines can effect a skin test, but do not effect a RAST or

ImmunoCap

blood test. The blood tests spot IgE, and the production of IgE is not regulated

by

antihistamines. If it was we wouldn't need Xolair. Prednisone is debatable from

what I have

researched. It may or may not effect IgE. Prednisone is a strong

anti-inflammatory,

promotes cell death (aptopsis), but it isn't known absolutely what it does to B

cell

production. Xolair can create false positives, but more likely the readings of

IgE will be

higher than your normal atopic base without Xolair. In other words my counts for

certain

molds were over 45ku/L on Xolair and about 15ku/L before I started to take it.

On the

former count it is just uncertain how much is bound by Xolair and left unbound.

About your banana reaction and no affirmation with RAST....RAST is not very

accurate.

The newer tests, like ImmunoCap, are much more sensitive.

I would be interested in labs that are able to separate the bound from the

unbound, as I

just talked to the lab for ImmunoCap, and they were not capable of it.

>

> Hello All,

>

> This is probably a 'duh' question, and I think I already know

> the answer, but I'm not compltely sure (I haven't had a RAST test in

> almost 4 years). Would having Xolair the day before, taking 10mg of

> Zyrtec & 7mg of Prednisone (I've been on it for 3+ years) 2-3hrs

> before RAST bloodwork cause false negative results? I am just so

> baffled by the results because I reacted to a Banana (in the skin) I

> broke out in hives, had to take 50mg of Atarax (it was interesting)

> and my allergist decided to run a 'Latex Panel' RAST because bananas

> apparently cross-react with latex. I got the RAST results yesterday

> (in a phone-call from a secretary, so I couldn't really ask her), the

> panel tested for bananas too, and I tested negative for bananas.

> Which is quite odd, and my mom was like " Well, that's a good thing, "

> but I don't think it is because at least if the banana test was

> positive, I would know to avoid bananas, but now I don't know what

> I'm allergic to. I have an appointment with my allergist in two

> weeks, and I'll ask him then, but I was just wondering if anyone here

> might know.

>

> Thanks,

> Meagan

>

[Guest guest]

Meagan,

The steroids at prednisone I know can affect the rast test . the test is not

very accurate either. I have a latex allergy feel free to email privately if you

would like. I no longer get xolair as I reacted to that as well.

----- Original Message -----

From: meagainbenny

Sent: Wednesday, September 10, 2008 9:33 AM

Subject: [ ] RAST question

Hello All,

This is probably a 'duh' question, and I think I already know

the answer, but I'm not compltely sure (I haven't had a RAST test in

almost 4 years). Would having Xolair the day before, taking 10mg of

Zyrtec & 7mg of Prednisone (I've been on it for 3+ years) 2-3hrs

before RAST bloodwork cause false negative results? I am just so

baffled by the results because I reacted to a Banana (in the skin) I

broke out in hives, had to take 50mg of Atarax (it was interesting)

and my allergist decided to run a 'Latex Panel' RAST because bananas

apparently cross-react with latex. I got the RAST results yesterday

(in a phone-call from a secretary, so I couldn't really ask her), the

panel tested for bananas too, and I tested negative for bananas.

Which is quite odd, and my mom was like " Well, that's a good thing, "

but I don't think it is because at least if the banana test was

positive, I would know to avoid bananas, but now I don't know what

I'm allergic to. I have an appointment with my allergist in two

weeks, and I'll ask him then, but I was just wondering if anyone here

might know.

Thanks,

Meagan

[Guest guest]

Having been tested by NINE different doctors over the last 30 years,

I can report that all of them have required me to stop antihistamine

and prednisone use prior to ANY type of allergy testing. I expect

that a number of folks who are steroid dependent have had tests while

still on prednisone, but those folks are probably sufficiently

allergic to test sufficiently positive to a number of allergens

regardless of what meds they may be on.

I agree with this poster about asking about whether or not the RAST

test you had could differentiate Xolair-bound from free IgE.

Addy

--- In , " billybaroo1958 " <cajjz109@...>

wrote:

>

> Ok, I will contradict what the other poster said about what meds

can and cannot effect a

> RAST test. Antihistamines can effect a skin test, but do not effect

a RAST or ImmunoCap

> blood test. The blood tests spot IgE, and the production of IgE is

not regulated by

> antihistamines. If it was we wouldn't need Xolair. Prednisone is

debatable from what I have

> researched. It may or may not effect IgE. Prednisone is a strong

anti-inflammatory,

> promotes cell death (aptopsis), but it isn't known absolutely what

it does to B cell

> production. Xolair can create false positives, but more likely the

readings of IgE will be

> higher than your normal atopic base without Xolair. In other words

my counts for certain

> molds were over 45ku/L on Xolair and about 15ku/L before I started

to take it. On the

> former count it is just uncertain how much is bound by Xolair and

left unbound.

>

> About your banana reaction and no affirmation with RAST....RAST

is not very accurate.

> The newer tests, like ImmunoCap, are much more sensitive.

>

> I would be interested in labs that are able to separate the bound

from the unbound, as I

> just talked to the lab for ImmunoCap, and they were not capable of

it.

>

>

> --- In , " meagainbenny " <bennetme@>

wrote:

> >

> > Hello All,

> >

> > This is probably a 'duh' question, and I think I already

know

> > the answer, but I'm not compltely sure (I haven't had a RAST test

in

> > almost 4 years). Would having Xolair the day before, taking 10mg

of

> > Zyrtec & 7mg of Prednisone (I've been on it for 3+ years) 2-3hrs

> > before RAST bloodwork cause false negative results? I am just so

> > baffled by the results because I reacted to a Banana (in the

skin) I

> > broke out in hives, had to take 50mg of Atarax (it was

interesting)

> > and my allergist decided to run a 'Latex Panel' RAST because

bananas

> > apparently cross-react with latex. I got the RAST results

yesterday

> > (in a phone-call from a secretary, so I couldn't really ask her),

the

> > panel tested for bananas too, and I tested negative for bananas.

> > Which is quite odd, and my mom was like " Well, that's a good

thing, "

> > but I don't think it is because at least if the banana test was

> > positive, I would know to avoid bananas, but now I don't know

what

> > I'm allergic to. I have an appointment with my allergist in two

> > weeks, and I'll ask him then, but I was just wondering if anyone

here

> > might know.

> >

> > Thanks,

> > Meagan

> >

>

[Guest guest]

Thank you both for your replies! I though that my meds might negate

the testing, but then I thought maybe I was thinking of the wrong

thing (I think too much!). I will DEFINITELY ask my MD and 'report

back,' but I was just wondering if anyone else had encountered a

similar situation.

Thanks Again,

Meagan

> > >

> > > Hello All,

> > >

> > > This is probably a 'duh' question, and I think I already

> know

> > > the answer, but I'm not compltely sure (I haven't had a RAST

test

> in

> > > almost 4 years). Would having Xolair the day before, taking

10mg

> of

> > > Zyrtec & 7mg of Prednisone (I've been on it for 3+ years) 2-

3hrs

> > > before RAST bloodwork cause false negative results? I am just

so

> > > baffled by the results because I reacted to a Banana (in the

> skin) I

> > > broke out in hives, had to take 50mg of Atarax (it was

> interesting)

> > > and my allergist decided to run a 'Latex Panel' RAST because

> bananas

> > > apparently cross-react with latex. I got the RAST results

> yesterday

> > > (in a phone-call from a secretary, so I couldn't really ask

her),

> the

> > > panel tested for bananas too, and I tested negative for

bananas.

> > > Which is quite odd, and my mom was like " Well, that's a good

> thing, "

> > > but I don't think it is because at least if the banana test was

> > > positive, I would know to avoid bananas, but now I don't know

> what

> > > I'm allergic to. I have an appointment with my allergist in two

> > > weeks, and I'll ask him then, but I was just wondering if

anyone

> here

> > > might know.

> > >

> > > Thanks,

> > > Meagan

> > >

> >

>

[Guest guest]

Hi All,

I went to my allergist/pulmo yesterday and (I should know this by

now), he is a physician speaker for Xolair, so he factored that in

before ordering the RAST testing, and apparently ordered a specific

form of testing where Xolair isn't as much of a factor. Now the

Zyrtec I took the morning of the test has NO effect whatsoever, but

the Prednisone I also took the morning of the test does have some

effect. The secretary/desk clerk who called me a couple weeks ago and

told me all the tests were 'negative' was only somewhat correct. The

banana RAST did show some reactivity, which was within the 'normal'

range, but my allergist told me that the Prednisone dampens the

response, so it was within the normal range for people not on pred,

but it means I am allergic to it. The rest of the 'latex profile'

would have shown some reactivity if I was allergic to those things

even with the pred, and every level except the banana tested at 0.00,

so I'm not allergic to latex or hazelnuts or any of those things. My

MD said that the Xolair binds to the IgE and deactivates it within

the body, but it is still 'active enough' in this test to show a

reaction.

So now I understand. Again, thanks so much for your replies. Its

so great to have a resource of people who know this stuff, thank you.

Meagan

> > > >

> > > > Hello All,

> > > >

> > > > This is probably a 'duh' question, and I think I already

> > know

> > > > the answer, but I'm not compltely sure (I haven't had a RAST

> test

> > in

> > > > almost 4 years). Would having Xolair the day before, taking

> 10mg

> > of

> > > > Zyrtec & 7mg of Prednisone (I've been on it for 3+ years) 2-

> 3hrs

> > > > before RAST bloodwork cause false negative results? I am just

> so

> > > > baffled by the results because I reacted to a Banana (in the

> > skin) I

> > > > broke out in hives, had to take 50mg of Atarax (it was

> > interesting)

> > > > and my allergist decided to run a 'Latex Panel' RAST because

> > bananas

> > > > apparently cross-react with latex. I got the RAST results

> > yesterday

> > > > (in a phone-call from a secretary, so I couldn't really ask

> her),

> > the

> > > > panel tested for bananas too, and I tested negative for

> bananas.

> > > > Which is quite odd, and my mom was like " Well, that's a good

> > thing, "

> > > > but I don't think it is because at least if the banana test

was

> > > > positive, I would know to avoid bananas, but now I don't know

> > what

> > > > I'm allergic to. I have an appointment with my allergist in

two

> > > > weeks, and I'll ask him then, but I was just wondering if

> anyone

> > here

> > > > might know.

> > > >

> > > > Thanks,

> > > > Meagan

> > > >

> > >

> >

>