Peanut Allergy Misdiagnosed in 2 Out Of 3 Cases

[LauraLoo]

From Medical News Today - April 13, 2010:
"In fact, our findings show that two out of three that are considered allergic to peanut only experience mild symptoms, if any symptoms at all. The reason is that these patients are not allergic to peanut, but to birch pollen."

http://www.medicalnewstoday.com/articles/185263.php

Apparently there is a better test than SPT or RAST that allows a closer look to pinpoint exactly what proteins are causing the reaction.

Has anyone ventured out to do this or know any more details about this testing? It looks like this type of testing (ImmunoCAP Allergen Component) is more available in Europe and is limited in the US.

I have to say that I am *very* tempted to give it a go for ds if I could find anyone in our area that is doing this type of testing.

[scsigrl]

I am currently looking into it. I have the name of the Dr. in the area who does the test but need to call and find out how much and if insurances are typically covering it. I have the info for the company who does the test and they can point you to a Dr. in your area if you are interested.

[changingseasons]

I guess I don't see the point. ?? If you have a reaction to peanuts, then what does it matter if it's the peanut itself or a pollen x-reactivity? (I didn't actually read the link, just responding to the part you quoted.)

If you are doubting a positive SPT or RAST result, you could always do an in-office challenge with an allergist (starting with just skin contact of course.)

[LauraLoo]

I think the difference would be if you didn't show any symptoms to the suspected food, but the SPT or RAST showed an allergy. I think this is why allergy tests are so unreliable because they don't look at the molecular level and why elimination diets are so tedious. To have 2/3 be misdiagnosed from a 10 year study of 4,000 kids is kind of......wow.

[LauraLoo]

Originally Posted by scsigrl

I am currently looking into it. I have the name of the Dr. in the area who does the test but need to call and find out how much and if insurances are typically covering it. I have the info for the company who does the test and they can point you to a Dr. in your area if you are interested.

Yes -- please PM me with the company info. I'm interested in exploring this.

[scsigrl]

http://www.pirllab.com/

I just sent customer service an email inquiring what Dr's in the area did this testing.

I think this is really important! I live in fear about a peanut reaction. My child tests + via blood and SPT. He has never been exposed though. SO are the blood and SPT REALLY +? We all know trial is the only sure way to dx an allergy. If this is one more piece to the puzzle as to if we are truly safe to try, I am all for it!

[changingseasons]

Originally Posted by LauraLoo

I think the difference would be if you didn't show any symptoms to the suspected food, but the SPT or RAST showed an allergy.

Well, that's kind of my point. If you've already been exposed and know that you don't react, but your test is positive- why wouldn't you just do a food challenge (in-office for peanuts!)? Any responsible allergist would recommend that in that specific situation, I think.

Also- you can look at the number on your RAST. Usually, the higher the number will mean more of a likelihood of reacting. If you had a high RAST number, and a large positive SPT, then I'm pretty sure you're allergic.

The other option... why not just get tested for the specific pollen allergy on your SPT?

I guess I just can't wrap my head around the "2 out of 3" thing. I mean an SPT is just taking the substance and putting into the upper layers of your skin. If you have a reaction to the substance on your skin, think of the reaction that will happen inside your body. Regardless of why you're reacting to the substance (either the protein or the pollen), a reaction is a reaction!

[scsigrl]

Are you likely to have an ana. reaction to pollen? I would want to know if it was a true allergy when you one is dealing with something like peanut which I understand is one of the most dangerous ana. reactions out there.

[changingseasons]

Um..... did anyone notice that the source of this article just happens to be the one and only lab in the US that does this test?

Just something else to consider before you run out and spend a bunch of money on this test.

[changingseasons]

Originally Posted by scsigrl

Are you likely to have an ana. reaction to pollen? I would want to know if it was a true allergy when you one is dealing with something like peanut which I understand is one of the most dangerous ana. reactions out there.

No, that's why I said if you knew you've been exposed and had no reaction, you could do the in-office challenge. Or just get tested for the pollen itself!

Even with an real IgE protein allergy, you aren't necessarily going to have an ana reaction. And you might have several minor reactions, then 10 years later have an ana reaction.

[LauraLoo]

RAST tests come back with a number of results -- not just the foods that are suspected. So, there could be a number of results that are just inaccurate. So, do you avoid these foods even though you aren't sure if they have caused problems or might cause problems in the future -- and maybe it isn't a food, but a pollen allergy, for example?

Not sure if you read the link -- this link highlights the birch/peanut protein similarities, but I can only imagine the numerous others. SPTs & RASTS don't look at the molecular level for the proteins -- they can't tell you which protein is causing the problem. Peanut and birch share one similar protein, but there are several proteins in peanuts. Frankly, I'd rather do a more intensive and thorough test, such as the ImmunoCAP test, initially than to try to food challenge since it is believed that allergies such as peanut become more intense with each exposure. Food challenges just wouldn't give me enough peace of mind.


From the link:
"Normal tests based on natural extracts from peanut or birch can only tell that the body is reacting to something in this complex mixture. Molecular allergy can precisely identify the protein that is giving rise to the reaction, making it possible to investigate the cause of allergy, discover false allergies, and find unexpected cross-reactions," says Dr. Wickman."

[LauraLoo]

Originally Posted by changingseasons

Um..... did anyone notice that the source of this article just happens to be the one and only lab in the US that does this test?

Just something else to consider before you run out and spend a bunch of money on this test.

I found the link to this article on "Kids With Food Allergies" website.

I think that most people agree that current RAST and SPT testing is not necessarily known for being very accurate. Why not try something that could be much more specific?

[LauraLoo]

Originally Posted by changingseasons

No, that's why I said if you knew you've been exposed and had no reaction, you could do the in-office challenge. Or just get tested for the pollen itself!

But how would you know it's a pollen to test for? That's the problem -- there are so many possible combinations.

[changingseasons]

Originally Posted by LauraLoo

Food challenges just wouldn't give me enough peace of mind.

Food challenges are THE gold standard in allergy testing. There is no test out there that is 100% accurate, I'm guessing including this one. So I would be concerned if you don't trust the food challenge but take these test results as gospel truth, kwim?

Originally Posted by LauraLoo

I found the link to this article on "Kids With Food Allergies" website.

Doesn't make it a valid/accurate source.

Originally Posted by LauraLoo

But how would you know it's a pollen to test for? That's the problem -- there are so many possible combinations.

(Again, didn't read the whole article- just skimmed), but I thought it was mentioned earlier that peanuts were cross-reactive for birch pollen, right? Or are there multiple pollens that could cause a positive peanut test?

The whole thing sounds really similar to OAS. People with OAS are reacting to the pollen rather than the protein in the food (as far as I understand it.) They are usually mild reactions, but even though it isn't a protein allergy, people CAN have ana reactions with OAS! Which is why I keep coming back to the question- why does it matter if you're reacting to the pollen or the protein? You really have no way to predict how you will react in a real life situation today, tomorrow, or years from now based on a test.

I'm really not trying to be argumentative or discouraging, I just get nervous when people put all their beliefs and hopes into what a test tells them, because I know first hand how inaccurate they can be.

[LauraLoo]

Originally Posted by changingseasons

I'm really not trying to be argumentative or discouraging, I just get nervous when people put all their beliefs and hopes into what a test tells them, because I know first hand how inaccurate they can be.

No - I know you aren't. I just think that there is something to be said for a test that bridges the gap between SPT/RAST and a straight out food challenge, which can also be very time consuming and costly for someone with suspected multiple food allergies.

DS, aside from his peanut and nut allergies, also tested IgE for soy. But he doesn't have ana. reactions to soy -- just an accumulation of head congestion enough to cause ear aches and intermittent tummy aches over time that we figured out months AFTER we pulled him off of soy. A food challenge wouldn't be helpful in this case. And potentially, he could outgrow his soy allergy but it would be hard to know since we could try a SPT/RAST (likely to be inaccurate), a food challenge (not likely to show anything,) or give him soy for a few months and see what happens. I'd prefer to have a more intensive test first before giving him anything to ingest - in or out of a dr's office -- something that may be more specific and reliable. Wouldn't you? I'm not saying that a food challenge wouldn't eventually be warranted, but it would give me peace of mind to have some other indication that it would be safe to try.

In any case -- found another article that talks about the molecular level of testing by this same company. It's way at the bottom of the article --

http://online.wsj.com/article/SB1000...194645130.html

[changingseasons]

Originally Posted by LauraLoo

I'd prefer to have a more intensive test first before giving him anything to ingest - in or out of a dr's office -- something that may be more specific and reliable. Wouldn't you?

Absolutely!!! I guess I'm doubtful because the only one I've seen telling us that this test IS more reliable than RAST or SPT is the company that makes it. Seems like great marketing to me, in this ever increasing food allergy business.