So confused...AGAIN

[IowaMom]

I am so confused by DD's allergy testing! Any insight/advice would be much appreciated.  A bit of history: she was dx at age 2 after a reaction (not anaphylactic).  RAST Levels:
2008-1.30
2009-.64
2010-.45
2011-1.85
2012-11.80
2014-Less than .35

In 2010 skin testing showed 18mm wheal. 
In May 2014 we did skin testing again after her low RAST, and it was 7mm.  HOWEVER, they said the histamine control didn't react as it should have, so it wasn't valid.  I had her off antihistamine for 1 week, they said maybe some was still in her system. SO, took her off for one full month and returned
In August 2014- Skin test was 16mm (histamine reacted normally).

Yesterday I took her in for skin testing (didn't re-do RAST d/t her anxiety issues, and didn't see the point after the last testing).

There was NO response at all to PN.  However, once again her histamine control didn't react how it should- it was just a small dot.  She has had NO antihistamines since last fall (at least 3 mos).  Again, they say it is not a valid test.

My question is this- she did have strep all weekend prior to the test, so she had a lot of Advil.  I've noticed that some allergy offices say to stay off anti-inflammatories prior to testing, however some do not. We were not told to avoid anything other than antihistamines. Could this have been the issue?

The only other difference is the location of testing- both times that the histamine didn't react, the testing was done on her forearm. When we took her back in August of 2014 they did it on her back. Could that make a difference?

Thanks in advance for any ideas.  At this point, we are going to do a repeat RAST sometime this summer, and repeat the skin testing in September

[PurpleCat]

   I love/hate allergy testing.  It is not 100%.  It varies with each and every patient. Regardless of the results, I find DD's always confusing!

I don't know about the histamine not reacting.  That has never happened to us.  I do know my DD has taken Advil before allergy testing and it had no impact for her testing results.

Our allergist does not repeat testing every year.  She says it is not a true picture of allergies to do so.  She repeats ours every 3 - 5 years unless a new allergen is suspected and then she will test for that.

An important number you did not share is your DD's total IGE.  Why is that important?  Well it shows the overall status of your DD's body, not specific to any one allergen, just all of them together.  It really is eye opening to look at that number and the lower that number is, the better. 

For us, knowing that number and how high it sits over time has sent us on this course of action.  My DD has been on allergy shots for environmental allergens for the purpose of lowering that total IGE number.  In doing so, my allergist believes it will weed out what might be false positives for DD or show she is no longer allergic to things we thought she was "mildy" allergic to.

And it is working.  My DD's total number is down.  She has passed an open food challenge to coconut!  Something I watched her react to when she was little on Easter Sunday!  Some if her tree nut numbers have come down, we can challenge pecan if we want.  I am hopeful some of her fruit numbers and or skin wheals will come down or even go away!

[Linden]

We've always had a valid histamine control but have had some "weirdnesses" in both SPT and RAST.  DS' egg SPT went from "whopping big" (as the allergist put it) to nothing, to whopping big again, to nothing again.  The second two tests were at a different allergists' office, so I don't think I can blame it on either office's test procedures.  He's been allergic to egg throughout, as evidenced by a failed baked egg challenge. 



   

[rebekahc]

I'm not sure about the histamine control not showing a reaction - perhaps their serum was old or stored improperly or something?  Even so, I think it's important to note that a SPT can stay positive for years after outgrowing an allergy.  Since you've had some very low RAST numbers and even a negative one, I'd want to do a RAST and then a food challenge if the RAST was still <0.35.

[IowaMom]

Thank you all for your responses.  PurpleCat, they have never done a total IGE test on her before- so I have no idea what that number is.  However, right now her environmental allergies are flared- so wouldn't that affect the result?  Particularly without having anything to compare it to? I guess I'm not exactly sure about how that works.  And rebekahc- as far as a food challenge they have thrown that around each time a test comes back low/negative, but then like last time we go back and her wheal is 18mm and they say no way.  Unfortunately that's a rather moot point anyway, because my daughter is absolutely against an oral challenge.  Her anxiety is super high and this scares her- I don't think we'd be able to challenge until she's older and has the motivation to get past her anxiety about it. 

[hezzier]

Wouldn't total IGE be done automatically with every RAST test?   It also seems to me like this would be a perfect situation to do component testing since her RAST numbers are for the most part low, but still has a strong skin reaction.

[Macabre]

Our allergist (in La Crosse, WI--Not sure where in IA you are) doesn't do SPT for food at all because of the false positives. 

Have you thought about a component test for peanut? That could be a great next step with your recent experience.

Also, when DS was little we used EMLA cream to numb skin before blood draws. Really helped!

[IowaMom]

I have heard of the component testing, but I haven't been able to find anyone here that will do it; even at the large teaching hospital that she goes to.  The last time I checked with them, this is the response I got:

"The test in which you are interested will need to be mailed to the lab that does them from whichever lab draws them.  I went to that web site and it appears that our lab would need to enter into a contract with them.  That would be time consuming.  The most efficient way for you to arrange that is to have a local allergist place the order through a lab that will contract with the specialty lab that performs the test in which you are interested."

Would I be able to get the component testing done at the same time as her RAST (IF I can find someone to do it?)?  And hezzier, they have never done a total IGE w/ any of her RAST testing.  They have only done the RAST.

[Mfamom]

i was also going to suggest component testing
my son also had lowering rast and inconsistent skin test results.  He had anaphylaxis when he was 4, so they were not on board with challenge even with lower rast.
He showed very mild on the component, we did challenge when he was almost 16 and he passed
I think you can have the test done at quest.  When we did it, the doctor ordered the uknow kit

[IowaMom]

After several phone calls, I think I finally found someone locally who will draw for the component testing!  I really hope this, along with re-doing the IGE and skin testing we will finally have some answers!  Maybe. I also know this may muddy the waters more.  I guess we shall see! Thank you all for your help. Love the support I get on this board!!

[Mfamom]

I think that if you get the component testing done you will not need the spt and rast.  The component test can actually give you accurate "risk" numbers
http://www.questdiagnostics.com/testcenter/testguide.action?dc=TS_Peanut_Component_Panel