Accuracy of allergy testing?

[staceyshoe]

DS is about to undergo some med testing for eating issues. On top of that, I've begun to notice that his behavior is completely out of control when he has more dairy (I think it's related anyway--still observing). Should I request allergy testing while we'll at it or it is pointless? I remember reading that there is a difference between a true allergy and a sensitivity, but there is a family history of milk allergy that presented differently from what I've seen in him. Since he doesn't eat solids and we are avoiding unfermented soy, it would be very hard for him to go DF. Getting a quick test just seems easier than trying to figure out how to eliminate and still get calories in him. WWYD?

[MotherWhimsey]

you could ask them to do it, it can't hurt to ask. But since he's under two years old, the tests aren't very accurate, so a lot of docs won't do them till after 2.

[Panserbjorne]

Under two they aren't very accurate, as the pp said.

You may still do it as you won't get false positives, but you'll get false negatives. Annoying, but it's a start.

I believe IgE reactions will be detected better than IgG reactions, but don't hold me to it.

[wendy1221]

Yeah, behavior problems are usually IgG allergies and most docs only test for IgE.

[staceyshoe]

IgG? IgE? Sorry, I'm brand new to all this. Is there a website you recommend that would help give me some understanding of terms and basic concepts?

[Panserbjorne]

Sorry, hon! It's old hat to alot of us here.

An IgE reaction is the classic idea of an allergy. It can affect respiration, skin etc but it tends to be immediate and painful. An IgG reaction is what people refer to as a sensitivity, but make no mistake it is every bit as dangerous. It generally effects the neurological system and the "reactions" you see are often delayed and not easily (at first) attributable to a particular food. You don't eat peanuts, say and have your throat close up with an IgG response. But it can cause all kinds of neurological problems and developmental delays.

My dd has IgE responses to shellfish and gluten, she has IgG reactions to dairy, soy and egg. I can't give her any of the triggers, but if she gets shellfish or gluten she gets huge welts that puss all over, itches to the point of scratching till she bleeds and screams uncontrollably. She will also swell in the face. If she gets soy, dairy or egg she gets a mild rash, gets irritable and acts out like you wouldn't believe.

[staceyshoe]

Thanks for that great explanation, Firefaery! What you said makes a lot of sense.

[jaidymama]

I have found that our insurance will only do the IgE test for kids under 4 ? And it has to be medically necessary... so in our case the doc just had to say it was necessary... pretty simple, straight forward there. However, we had heard of a test where they could use drops of blood from a finger prick versus doing a blood draw... turns out that test we had was for the IgG response only. And that IgG test was NOT covered by our insurance (although it is covered by the low income health insurance in our state.....) and is only offered by Naturalpath Physicians (at least in this area).... They used to do (or still do) skin prick tests where they would prick the skin, on the back, with a bit of the allergen to see how the skin would react... our insurance says they don't test kids under 4 in that way.

So my recommendation would be to have the allergy test done as well, but I would contact your insurance company and consult your doctor about this. IF your doc isn't wanting to test for allergies, then call around until you find someone who agrees that it is necessary. Not all docs agree about allergies... I had a friend who was told by her pediatrician that kids under 4 don't get allergies ?????: : : :

Good Luck!

PS. DS was a horrible eater for all his life... now that we know what to avoid, he has been eating lots of food and even asks for MORE food! I would also consider using behavioral and sleep patterns as possible signs that it could be an allergy.

[staceyshoe]

I appreciate that advice, Heidi. I've had to pay out of pocket for lab work before so know how quickly it adds up. I will definitely call our insur co first. It would be wonderful if dietary changes are all we need for ds to eat. (I hate even thinking about the possibility that it would require surgery or Rx meds. )

[yllek]

Originally Posted by firefaery

Under two they aren't very accurate, as the pp said.

You may still do it as you won't get false positives, but you'll get false negatives. Annoying, but it's a start.

: Our allergist told us it was the other way around. DS was tested for a whole slew of stuff just before his 2nd birthday. Test came back barely positive for walnuts (when I witnessed a huge, immediate reaction just after he consumed some raw walnuts) and very positive for soy and eggs (when he's never, ever had any type of reaction, behavioral or otherwise, to those foods). Our doctor said that false positives were common, and to just go ahead and give ds soy and eggs, but to stay far, far away from walnuts and pecans. I just asked what good is the RAST test then, if its results are so inconclusive. He didn't have a good answer for that. :

[Panserbjorne]

Sorry, I was talking about blood tests. Everything they came back positive for, they absolutely are allergic to. However dd didn't test positive for dairy (she was under two) and is most definitely allergic to it. Everything I read said that this was par for the course.

[Pauli]

My dd had a blood test at 9 months and skin prick tests at 9 1/2 and 10 1/2 months with accurate results (tested by elimating the things we hadn't and adding back in the things we had suspected but been wrong about). But the doctor said that it's not accurate for all kids. We did it because it seemed as though she was allergic to all food, the elimation diet didn't work for us because she had so many allergies and because one of them was rice.

I've been gone for a month...what kind of eating issues is your son having? (My daughter is 2 and barely eats solid food). If you suspect food allergies, I would totally do the test. It may not be definative but WILL give you a starting point. IF he's allergic to dairy, that is something you should know even if it complicates his diet. There are alternatives out there for dairy and soy allergic babies....

[Joyful Mama]

you can't get false positives? my story....

DS had allergy testing at 7 months after a lot of gastrointestinal issues (reflux, etc.) and major rashes...i had cut dairy out of my diet at 4 months (subsequently became vegan), and it had an enormous impact on DS's demeanour. his rashes went away.

so, he had the testing (dr. set up the app't), and tested positive (skin prick test) to SOY and WHEAT, but dairy didn't show a reaction. several months later, he had a blood test to the soy and wheat, and, as i suspected, they were both negative. however, i'm still convinced that he has a dairy allergy. if he has anything that has a BIT of dairy in it, he gets CRANKY and a terrible bleeding rash on his bum within 24 hours, guaranteed.

just wondering why the soy and wheat would have shown positive. and what you think about the dairy allergy...TIA!

[Panserbjorne]

A skin prick test is NOT a blood test. You can't get false positives with a blood test. You either have the antibody or you don't. You can get false negatives (the antibody in question wasn't tested for, there wasn't enough or wasn't a measurable amount etc.) but if you have the antibody, you have the antibody. That is why I recommend blood tests.

[wendy1221]

Originally Posted by firefaery

A skin prick test is NOT a blood test. You can't get false positives with a blood test. You either have the antibody or you don't. You can get false negatives (the antibody in question wasn't tested for, there wasn't enough or wasn't a measurable amount etc.) but if you have the antibody, you have the antibody. That is why I recommend blood tests.

Thanks for pointing that out! I had a RAST done earlier this year and both my egg and milk allergy came back negative! I've been ever since! I have always been allergic to milk and egg, and I couldn't see how they could have disappeared just like that. I'd never had a blood test done before. I had been 100% milk- and egg-free, cooking 99.99% from scratch in the months before having the RAST drawn. So maybe b/c I had been completely free of them completely for so long is why I tested negative? Good to know! I had wondered if that was it, and even asked if I had to be exposed to the allergen in order to test + for it, but I was told no, if I was allergic, it would show up.

[Panserbjorne]

Different tests, different requirements and different levels of accuracy. That's true with a blood test-dd was nursing almost exclusively and had allergies to things *I* have never eaten before. Weird. BUt the test we did is very accurate and totally worth it. She was under two and tested negative to dairy and is dairy allergic-but they told us to expect false negatives, especially at that age.