Test results


If you want to catch up more you can read my burried post titled "My friends 4 yr old daughter had first reaction" Her daughter had a very bad and scary reaction while eating mixed nuts. She has always had nuts in her diet. I got no responses so I guess I will try a new topic and see if anyone has any thoughts. So her skin test results came back at an 8 for bazillion nuts and a 2 for peanuts. I was unfamiliar with the test as my sons spt was only rated up to a 4+. Then she got blood test back that showed negative to both!?! Her doctor was baffled and is testing her again in a month. I said maybe the antihistamines from the initial reaction caused a problem with the test. It was three days prior and had a large dosage due to the severe reaction. any thoughts?

[This message has been edited by qdebbie1 (edited May 30, 2007).]

On May 30, 2007

I've heard that SPT often give false positives and the blood (RAST) tests can give false negatives. I also thought that antihistamines can influence SPT results, but not the blood tests. Could be wrong, though.

If this was her first reaction to nuts, then maybe there just wasn't enough IgE in the bloodstream yet. The fact that she had a positive SPT indicates that the IgE has attached itself to tissue. So my theory is, she had enough IgE to bind to internal tissue to cause an allergic reaction, but not enough "free" IgE in the blood to significantly register on the RAST test.

It would be a good idea to run those tests again in about a year to see where she stands. Until then, of course, avoid nuts.

I'm not giving medical advice, just an opinion.

[This message has been edited by Stephie's Mom (edited May 30, 2007).]

On May 30, 2007

Our allergist will not do any allergy testing right after a reaction because she says it's inaccurate. After DD had a near fatal reaction we had to wait about 6 weeks for her immune system to "settle down" before having her tested. We've always been told no antihistamines for at least 5 days before either skin or rast testing. Our allergist also says the most accurate dx of allergy is history, not testing. If you've reacted you're allergic - period.


On Jun 1, 2007

I would say that antihistamines 3 days prior to SPT would cause negative SPT's.

It does NOT affect RAST (blood draw)

SPT's go from 0-4 (or so) RAST goes from .35 to >100

My thoughts? If one test is negative, and one is positive, one is wrong. Dont do that one again.

Therefore RAST is a false negative. >IF< you think that the child reacted to the allergen tested for.

There you go. JMTC


------------------ [b]* Beyond Obsessed * [/b]

On Jun 2, 2007

Thanks I always enjoy the opinions of Jason. [img]http://uumor.pair.com/nutalle2/peanutallergy/smile.gif[/img]