Allergy vs. Intolerance?

[Wisteriacow]

I'm hoping someone can give me a quick rundown on the difference between a food allergy and a food intolerance. 2yo DS has known issues with dairy and nuts. He'll have a reaction even if it's something I eat and is then passed to him through breastmilk. His "reaction" is a red ring with a some raised areas around his anus, loose/foul smell bowel movements, trouble sleeping and out of control hyperactivity bordering on aggression.

He has an appointment with an allergist scheduled for Monday. In preparation of that his pedi (who's previously been dismissive of the food issues) offered to write a lap slip to have blood testing done for the food allergies. The results of that were all absent/undetectable for every single category.

I remember reading a difference between IgE and IgA but I don't remember what that means. Could he have allergies that are digestive reactive instead of immune system? Or is that simply a food intolerance not allergy? Would that type of "allergy" show up on a skin prick test?

[FAmom]

You can have allergic reactions that are gastrointestinal.  That are absolutely a result of an allergy.  That are not an intolerance.  And, that you need to treat with the appropriate medications.  

At 2yo sometimes it is difficult to have conclusive results on things also, skin prick or RAST.  Frankly, you can have some inconclusive results at almost any time.  My egg allergic child tests so low that most allergists tell us he isn't allergic.... and we've done a few oral challenges that ended up with him reacting.  The allergists basic proclamation then is "oh, guess he is allergic... don't feed him eggs"..... 

The most important thing I thought of when I read your post though was that you trust your gut when it comes to how you feel..... meaning, dismissiveness isn't something you should be okay with.  If you feel there is something going on, you go with it, and if you need to find a new doctor, then so be it.  Whether it ends up as a confirmed food allergy or intolerance, a dismissive or indifferent doctor isn't a good thing, especially when you are dealing with trying to help out a little one who is going to suffer the consequences of eating something they shouldn't.

As for the IgE/IgA..... all of that makes my head swirl.  

[changingseasons]

A skin prick test will only show you "true" (IgE-mediated) allergies, it won't show you intolerances (IgG or others.)  The symptoms really can overlap between the two, with the major difference being that a true allergy can lead to anaphylactic shock and death.  But both can cause problems with digestion, skin, sleep, behavior, etc.  One other difference is that usually (I'm bolding "usually", because this are exceptions) a true allergy will cause symptoms within minutes to hours (often within seconds of eating or contacting a food), where intolerances are usually a delayed reaction- from hours to days after exposure.

Skin tests are sometimes more sensitive than blood tests, so you might get different results.  But like the pp mentioned, observed food reactions ALWAYS trump test results- so if you know your kiddo reacts to something, then he IS allergic/intolerant, no matter what the test says.  

(There are also IgG tests that will show intolerances - ELISA and ALCAT are two - but they aren't all that accurate ime.)

[subtlycrunchy]

Good article from Healthy Futures (Doris Rapp, MD) defining allergy, intolerance and insensitivity .  It's no fun at the beginning becuase the world of allergies can be very confusing. But it all clears up -- good luck to you!

[Wisteriacow]

Thanks for the responses. We got the skin prick testing done and he was negative for everything they tested. It loos like we are indeed dealing with intolerances instead of true allergies. In some ways its a relief to know it isn't likely to be life threatening but it's still a lot of unanswered questions. I think we're still going to try a consult with a pedi gastroenterologist just to confirm that it isn't something else more serious.