Help! I don\'t understand RAST results!


I have been reading all of the posts about the RAST tests on this site. I have gotten so much advice in general about how to cope with my 5 year old's PA. I find I still have questions about the RAST test. She tested positive on the skin test but we recently had blood work done for what was described to us as a RAST test. I do not know how to tell if it was a CAP RAST test. How would I be able to tell? I am not pleased with my allergist, who rushes us out the door and does not return phonecalls. He has explained nothing to us. There are columns on the test results labeled LU, Allergen, and Class. What does LU mean? I can't find anything on the internet about LU. I see that a lot of you reference a Class level of 5 or 6...but this test printout only has a range of 0 - 4. My daughter has a >300 on the peanut allergy and 215 on milk. Her Class for peanut was listed as a 4 and her class for milk was listed as a 3. Are these CAP RAST test results? If they aren't, should I go further and find an allergist who offers that test instead? We realize our daughter is severely allergic to peanut and have known this for 2 years (and we take all necessary precautions) but I am now trying to figure out if she could go into anaphylactic shock from ingesting milk...we have been avoiding it as much as possible. She has never had a reaction in the past. She scored a 3 on several other foods, as well. I feel like it isn't safe to feed her anything!! The allergist didn't explain any of this to us. HELP! Your thoughts would be soooo appreciated. I have chewed my nails down to the bone.


On Oct 20, 2006

There have been quite a few RAST discussions in the last few months. If you click on the "search" in the upper right part of the main page, you can search by keywords.

Here's one discussion that might help:


Take care, Daisy

On Oct 21, 2006

Those don't quite sound like ImmunoCAP numbers. I think what you really need is to find a new allergist who will explain test results and help you develop a plan of action for your daughter's diet.

edited to add:

Here is a page that explains a RAST that sounds like the one your child had:


It looks like the units are not LU but IU (international units).

I searched some more and found a test that does use LU (luminescence units). It is here:


Here is a table I pulled out of that document:

CLA Class Net LUs Allergen-Specific IgE Concentration 4 >242 Very High 3 143-242 High 2 66-142 Moderate 1 27-65 Low 1/0 12-26 Very Low 0 0-11 Nondetectable


[This message has been edited by Momcat (edited October 21, 2006).]

On Oct 23, 2006

NEVER heard of this. Dont know HOW reliable, kwim? Sounds legit, though, similar to RAST it says.

maybe its reliable. Gave you scores.. use as a guideline, I s'pose.

Thnx for hunting down that site - lots to read [img][/img]

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

On Oct 23, 2006

Thank you so much - I don't know what I would do without this site. I feel so lost most of the time. We are in the process of finding a new allergist who can hopefully shed some light on all of this. You are all wonderful!!!