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Rast testing and IGE levels

43 replies [Last post]
By Margo on Mon, 04-05-99, 22:39

For all you experts out there...
If you take all peanuts and peanut products out of your diet will
IGE levels naturally go down on RAST testing and up again if peanuts are again eaten.
My son's RAST results went from a high 4 to a
low 2 after 6 weeks of being peanut free.

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By CindyBarnes on Mon, 04-05-99, 23:33

Good question, I don't know and was wondering that myself.

My son's went down 200 "points" within 1 month (he almost went down 1 class); made me think it might go down more if he didn't have any peanuts. We will probably have him tested in a year just to see what his score says, so we should know more then.

I'm not sure how much you should read into these RAST scores. Our allergist indicated it didn't indicate reaction severity, just that a higher class was more likely to suffer a severe reaction. However, from my understanding, class 2's could have as severe a reaction as a class 6, it's difficult to tell.

It seems to me that if you're able to keep yourself or your child away from peanuts for a sufficient length of time, the allergy *might* go away, or could become less severe. (We do know it can get worse the more exposures a person has.) I haven't seen definite information about that, but our allergist said something like, "your son will have this allergy for a long time." He didn't say that he would have it for the rest of his life like everyone else and every single article I've read has been saying. (I pointed this out to our allergist, that he was the only one who has said that and he didn't change his statement.) So, I've been hoping that if our son's RAST score keeps going down that he *might* become less sensitive.

I have to say that it's all very confusing and just when I think I understand what's going on, I read something on this web site that changes my opinions. Everything I'm typing in this post is also wishful thinking based on sketchy information and comments I've pieced together, but it's all I've got right now!


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By sophiesmom on Tue, 04-06-99, 13:09

This RAST score really confuses me, because if their is any correlation to eating peanuts and the score then how do I explain my daughter being a high 5 and having only one exposure at least a year prior to testing. I have eliminated more from her diet(all chocolate and suspect cross contamination items) since the testing. Could she have been exposed through cross contamination and that explains her high score. I never let her have any peanut products at all even though we didn't know she was allergic due to a lot of allergies in the family. So as far as I know she only had that one ingestion at 2 1/2, and at 3 1/2 scored high 5 on the RAST test. I want to test her again just to see how she has done in the last couple of months, but my allergist doesn't seem to think the score indicates what kind of reaction she would have either. I don't know I would feel more comfortable being a 1 than a 5 even though I wouldn't do anything differently.

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By CindyBarnes on Tue, 04-06-99, 15:09


Well, your story blows my wishful theory out of the water. I do know that children under 5-7 years of age are very unpredictable when it comes to food allergies, so that's probably why the allergists don't like to test them. Also, despite our allergist telling us not to pay too much attention to our son's RAST score, my husband and I refer to it often. That's probably another reason why they don't like to test small children! The one thing we were able to confirm with the RAST test was that he was sensitive to peanuts, so we should probably just leave it at that.


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By janeliz on Wed, 04-07-99, 02:01

Julie - At six months old my son was a category IV (360 was his score). We just had him retested and will get the results on the 15th. I will let you know if we have the same experience. I have done my best to avoid peanut products, but as some of the others I am unsure about those "unknown contaminations" that we may have had. I can say that at six months of age and with no teeth I have a hard time believing that my son ingested peanut products in his baby food. Unless of course baby rice cereal has peanuts in them???


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By CindyBarnes on Wed, 04-07-99, 02:32


How old is your son now? What is your motivation in having him retested at this time?

(We plan on testing our son often -- every year or every other year -- just to keep tabs on things.)


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By Margo on Wed, 04-07-99, 14:04

I just wanted to say that I know that going from a class 4 to a class 2 does not mean the severity of the reaction will be less or that he is any less allergic. To me it just means that there are less IGE antibodies to peanuts floating around in his blood. So we must be getting most of the peanuts out of his diet. Remember my son has
eosinophilic esophagitis and does not react externally. I also hope that by reducing the IGE antibodies we will also reduce the eosinophil count and his esophagus will heal.

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By janeliz on Thu, 04-08-99, 00:01

Tracy - We are retesting Spencer who is 18 months old because we continue to have problems and the allergist (who we just started seeing) wants a complete picture of what we are dealing with. We decided to do the RAST and not the skin test because my active boy was having trouble handling the consultation visit let alone getting pricked (no matter how quick it may have been). We plan on doing the tests once a year (I believe) because the allergist said that children this age (until approx. 5) change and exchange allergies. He said generally the egg and peanut allergies stay but most others can vary.

We had Spencer's 18 month check with the PED today and when I mentioned that we had met with an allergist (without asking him) he almost seemed relieved. Everyday I feel like I did the right thing by making that call!

Thanks, Kelly

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By sophiesmom on Thu, 04-08-99, 15:58

Just to make life even worse for me, I found a deer tick on my peanut allergic daughter. It is off to the lab for testing but my ped. will draw bllod in two weeks anyway to check for lyme disease. Since I'm getting blood drawn anyway I am going to have them run a RAST test on her again for peanuts. It's only been two months since her last one, but since having this discussion I am curious to see if there is any changeand what it is. Then I will discuss the numbers with my allergist to see what she thinks. Maybe I will get some more insight on what this number means.

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By Mike and Missy on Wed, 04-14-99, 16:02

I am taking my son (27 months old now) back to the allergist to have him tested with the RAST test for tree nuts and I would like to test for shellfish also. We had him tested in Jan. 99 for peanuts on the RAST. I believe Tracy had the same situation (She went back for more tests). When I asked the allergist if he was going to test for anything else in Jan. he said no. I just sat there like a dummy and didn't complain. When we take him back to the allergist soon (the same one, unless he refuses to retest), I am going to ask to him to also test the peanut again while we're drawing blood.

Does anyone know if it takes more blood to be drawn to test more things?

And does the child have to have been exposed to tree nuts in the past for the RAST to register an allergy?
Bottomline, I will let you know of the new RAST results.
Any advise before I go back?


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By Byrd on Wed, 04-14-99, 17:54

IgE sticks onto cells such as mast cells and basophils AND STAY THERE FOR A VERY VERY LONG TIME. These are the antibodies that cause allergic reactions and anaphylaxis. I'm not sure of the value of measuring IgE free in the blood. It is the IgE sitting on cells that is the problem. Maybe that is why the RAST is not a good predictor. How much do these tests cost and what companies produce them?

[This message has been edited by EILEEN (edited May 22, 1999).]

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By dkk on Sat, 05-22-99, 03:17

I just found out about my allergy at 26 years old. I was eating crunchy peanut butter on saltines every night as a snack and all of my make-up contains peanut oil.

I scored a 6 on My IGE and my peanut blood test was a 969. What does this mean?

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By dkk on Sat, 05-22-99, 03:20

I just found out about my allergy at 26 years old. I was eating crunchy peanut butter on saltines every night as a snack and all of my make-up contains peanut oil.

I scored a 6 on My IGE and my peanut blood test was a 969. What does this mean?

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By pratt on Mon, 05-24-99, 12:18

Hi Everyone! We recently brought Sean to be retested for his allergies. I was hoping the first test was wrong and that maybe by some chance, he wouldn't have an allergy. My family thought I was ridiculous given the anaphlaxis he has experienced but I was just hoping. Anyway, to our surprise, his IGE levels have gone down. He has gone from a 3=peanut to a 2=peanut and a 4=egg to a 3=egg. I was told however that this does not make the anaphylaxis any less threatening. It may have something to do with the fact that he has not been exposed to these products. Nonetheless, it is still there. Lynda

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By sophiesmom on Mon, 05-24-99, 15:52

Hi everyone! Unfortunately I had the opposite experience. Remember I had to take my daughter for blood work because of a deer tick. I talked my pediatrician into writing up a RAST test prescription. Anyway after only homemade cooking and no chocolate or anything that could be cross contaminated (i even went as far to buy only Kelloggs cereal with the bar code from peanut free plants). To summarize I think I did anything humanly possible to protect her from cross contamination and she is now a level 6 and off the chart with her IGE level. She was a level 5 two months ago. I also unfortunately tested her for a lot of other things that my allergist advised me not too. She is only 3 and my allergist said it was not worth testing her for other things until she is 6 or 7. Anyway I made an appointment with my pediatric allergist to discuss what I did with my pediatrician. She explained to me again that she puts no merit to these RAST scores and that they will fluctuate. The number means nothing. She is more interested in a case history. Also she said sometimes being ignorant is helpful in the case of allergies. She would have preferred that I not test her for other foods, but now that I had (and PS she showed a high allergy for EVERYTHING that I tested her for i.e. soybeans, strawberries, coconut, all tree nuts, etc.) I should try to avoid these foods even though some she never showed a reaction to before. She had soy formula as a baby. For you soybean allergic people she said soybean oil is ok just not things like bean curd and other soybean products. Also she did not see anything in particular with my sunscreen, but did advise to just avoid it and that the sunscreen was probably what caused the rash. Also as a humorous (?) side note, my husband who came to the appointment with me was having a bad case of seasonal allergies and she skin prick tested him for 8 things (hayfever, mold, etc). She was so impressed with his immediate and huge response to everything. She said she has never had anyone so allergic before in her office. The whole appointment then ended being about my husband. Well I feel like I am back at square one with her and I will continue to avoid products. I am also thinking of learning more about this cap rast test.
Thats all for now.

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By KIMBERLEYJO2001 on Mon, 05-24-99, 16:45

The RAST has excellent sensitivity and negative predictive accuracy but poor specificity and positive predictive accuracy. In other words, there are very few false negatives and a large number of false positives. This is why the allergist combines the RAST test with a history. For example, the RAST test indicated my son was somewhat allergic to milk, however has/is not experiencing any clinical symptoms.

Here is the URL for the abstract of the study I got my information from.


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By Maggie Z on Mon, 05-24-99, 18:16

The RAST test is really very misleading. False positive always come up, and their grading system seems too sensitive. For the person with the 969 result- dont panic yet, my test 6 months ago revealed a RAST number of 36,000+, and yet I dont have an inhalation allergy to peanuts. My problem is that my allergist isnt sensitive to my worries about the test. Im switching allergists now, because of it. There needs to be better explanation of what these test mean.

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By alijen on Fri, 06-04-99, 01:24

I took my 18 month old last week to get another RAST test, I asked for a CAP-RAST but the scoring system seemed like the old test so I am not sure. At 12 months old his peanuts were a class 4 and ige levels 746 and this time he was a class 2 and ige levels 216. He tested a class 1 for hazelnuts and brazilnuts, but has never been exposed to them. It seems like his numbers for peanuts went down alot in 6 months, that it gives me a litte hope. I know they say you never outgrow this allergy. This test is so confusing!!

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By fsage on Fri, 06-04-99, 03:09


[This message has been edited by keri (edited June 07, 1999).]

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By KIMBERLEYJO2001 on Fri, 06-04-99, 11:33

The RAST test does not predict severity of reaction. All things being equal, a level 5 has a higher probability of a severe reaction than a Level 3. A couple prime factors regarding severity are route of exposure (e.g. touch or ingestion), the amount of exposure, complicating medical conditions (e.g. asthma).

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By fsage on Fri, 06-04-99, 16:53

point well taken looking back in my post (wow, i sure get carried away) i see i should have stated that as an opinion rather than fact. I still do think it is a better indicator of future problems for many reasons, but you are right - and actually looking back at old posts i see how very knowlegdable you are and how informed and i would go with your facts as oppossed to my opinions any day. i am learning new things daily on this site. thanks.

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By nkepe on Fri, 03-17-00, 01:34

We had an allergist appointment today, in hopes of getting our son tested for a latex allergy (PA diagnosed 2 years ago). This is a new allergist - not by choice - we moved. Anyway, somehow the order was not given to test for latex, only peanut, oat, and 2 types of dust mites (PA we already know, and oat isn't a concern, nor dust!!), and there were 2 other things listed on the order - one being Ige and the other a CBC. Can anyone help me out with those last 2 things? I really don't completely understand the IgE test - what does it show specifically as far as allergens? And I'm still at a loss as to why the latex test wasn't ordered, even though that was our primary reason for the visit today. The blood was drawn at a hospital, not at the allergist's, so I didn't learn of the 'missing' test until we were at the hospital. I know no one can help me with that part - I'll call her tomorrow to find out what happened - but thanks for letting me vent a bit!! My question again is what is the IgE for in regards to allergens, and what about the CBC?

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By Kellysmom on Fri, 03-17-00, 06:34

IgE stands for immunoglobulin E and the levels of IgE can somewhat indicate the severity of ones allergies from what I've been told. High IgE levels = more/severe allergies. CBC stands for complete blood count and checks blood levels for lots of things and is pretty standard for physicals, etc.

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By gymmie on Fri, 03-17-00, 16:05

Jan (or anyone else who knows),
What is the difference between the RAST and CAP RAST?

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By nkepe on Fri, 03-17-00, 16:33

So the IgE shows the severity levels for ANY allergies - none specifically? Is the IgE something that shows a person's probability of having allergies IN GENERAL? By the way, I contacted the lab and the allergist's office this morning - the lab received a verbal order for the latex test. Glad we got that straightened out!! Thanks for your info!
As a side note... after reading all this info about the RAST tests, I'm not sure they're really worth it.?. If they're not truly conclusive... depending on exposure, etc... I just don't know. This all gets so confusing at times!

[This message has been edited by Tammy James (edited March 17, 2000).]

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By Kellysmom on Sat, 03-18-00, 05:33

Here's the definition of IgE I found searching the web: IgE is the antibody which produces typical allergy or immediate hypersensitivity reactions such hay fever, asthma, hives, and anaphylaxis. Its "normal" function seems to be in anti-parasite defense.

As far as the RAST test goes, our allergist used it to confirm Logan's skin test results. If both are positive and similar classes then they're probably accurate.


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By MOMMY5 on Tue, 03-21-00, 22:26

Two things: 1) I was told my son could go anaplyatic with the allergy testing. Any thoughts? 2) I'm told my son might grow out of his peanut allergy... but i've not about to feed him peanut butter just to see! I'm wondering if allergy testing would give an indication?

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By Kellysmom on Wed, 03-22-00, 05:49

Your son could have an anaphylactic reaction from a skin test because he would be exposed to the allergen. The RAST test is a blood test done in a lab and therefore no allergen exposure.

Although the tests can usually tell you if you have an allergy, they are not reliable indicators of the severity of a reaction.

It is highly unlikely your son will ever outgrow his allergy - very few people do. He will probably be accidentally exposed sometime and you'll know then if he is still allergic. I would never do a peanut challenge with myself or my son.

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By Hudson6 on Wed, 03-22-00, 20:31

I am confused, why is this test being done so often on so many of your children?

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By nkepe on Wed, 03-22-00, 21:50

Our first allergy test came after 2 exposures (peanut butter injestion) at 18 months of age. That was a skin prick test. We moved and now have a different allergist. Our son is now 3 1/2 and his new allergist has requested a RAST test for him. Drs. are all different. I personally don't know why this allergist wanted him "retested" this way. To each his own, I guess. He will also be tested for other things besides PA (he has been having reactions to other things lately, and we're trying to figure out what is causing it exactly).

[This message has been edited by Tammy James (edited March 22, 2000).]

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By jackOjack on Sat, 03-25-00, 04:29

Now I'm really confused!! I just took my 3 year old son for his first RAST test. He had an allergic reaction to peanut butter when he was 18 months old, and we haven't exposed him to any peanut products since then. Our Ped advised us not to have him tested until he was 3 yrs old, but we have always had the epi-pen just to be safe. Now is it due to expire, and are getting him a new one, but I guess by question is...do we trust the RAST test, as we have not exposed him to any peanut products for so long. I feel I have received more info from this website and all of you PA kids parents then from my own doctor and I thank you for that! I know my own government does not take this issue seriously!


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By dg975 on Tue, 03-28-00, 19:29

My PA daughters IgE level was extremely high. My allergist told me (beside her peanut allergy) her eczema increases the levels. He said people with eczema tend to have higher levels. He also said what I've read here, the level only indicates the severity of allergies in general - not specific ones.

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By bboehm on Wed, 03-29-00, 17:25

All the RAST test information is getting confusing. There seem to be some many different measurement scales. My son had a very small skin prick response to peanuts, but his peanut RAST was conventional Class 3, Modified Class 4 (638 on a scale of 0-6000). His score for rice was 113 (we were told this suggests a minor allergy), and all other scores were <70 (milk, wheat, soy, corn). Is anyone familiar with that type of scoring. I asked the nurse to clarify if it was a CAP RAST, or a regular RAST, but she did not know.

My son had never had a reaction to peanuts (that we know of) and he has never ingested peanuts. He is only 7 months old. He did have a skin response (hives) after being touched by someone who handled walnuts.

We are now very careful. We have removed all peanut and nut products from our house. We carry an Epipen and Benadryl. We realize this has changed our lives.

If anyone has any clarification on the RAST testing, I would appreciate it.


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By jackOjack on Sat, 04-08-00, 03:21

I would also appreciate any information about the RAST test. As I said in my previous post we just had our 3 year old son tested on March 23 for the first time. We were told at that time that we have to wait 21 days for the results. I'm not sure why it takes so long but I am very anxious for those results! Our Ped told us that if the RAST test shows that he is is PA, then no more tests will be done and we will live accordingly. If it shows he is not, then he will still have to have a skin test in the doctors office. That part seems scary to me, but the doctor says we will have the epipen there just incase! I sure hope we are doing the right thing for our son...like I said, any information would be greatly appreciated.

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By cshames on Sun, 09-10-00, 01:51

I've seen a few postings asking about RAST tests and IGE levels, but I still have a question that someone might be able to answer. My daughter got hives on her back when I nursed her after eating peanuts out of my hands when she was about 3 months old. (It was hot so she had only a diaper on - my hands were directly on her skin as I was holding her.) It made me suspect peanut allergy, though my husband thought it might have been bleach or some other cleaning chemical - or simply the heat. It went away after a little Benadryl and about 15 minutes. Then at about 10 months, my mother gave her a bite of dry toast with peanut butter on it. Soon she had a little hive next to her mouth where the crust had scraped her. (She does get slight welts whenever her skin's scraped.) She has no other health problems, incl. allergies, asthma, or eczema. I asked her pediatrician to test her blood at 1 yr. The Dr. ordered a peanut rast test. The lab bill says they ran an "aller. spec. IGE (QN)" and the Dr. said "the rast result was .58." This number (.58) doesn't look like any I've seen on this BB. Those numbers seem to be either between 1 and 6, or in the hundreds. Now for the question: Does anyone know what this .58 is? Is it the rast result, or the level of IGE in her blood? This was not a CAP RAST, as far as I know. The pediatrician said .58 was low, but prescribed an EpiPen. The allergist she sent us to said "just keep her away from peanuts. I don't think she needs an EpiPen right now." She had no other reactions to the skin tests (he didn't test peanuts).

Sorry to be so verbose. Any thoughts would be appreciated.

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By dtevenmalk on Tue, 09-12-00, 04:22

Some of you may be interested to read a report in the "Research" board called "United Kingdom Dept. of Health Report". It includes a discussion of tests such as the RAST. It also studied the connection between a genetic predisposition to Atopy and peanut allergy. It is worth reading. Hope this helps! And it trys to answer the original question...I believe it said that an infant not exposed to peanut could have a positive RAST because peanut allergy is related to a genetic history of Atopy which predisposes the individual.

[This message has been edited by Laura J (edited September 12, 2000).]

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By Suzi-Q on Fri, 09-15-00, 13:01

My son has just been diagnosed with PA. He had one reaction at 1 yr. old and at 18 mos. was suffering from chronic hives. We took him to an allergist for the hives and hed him tested for 17 allergies. PA was the only positive result. The allergist did the scratch test on him, and said that we would watch him and decide later if we would perform the "blood tests." We carry an EpiPen and keep him away from peanuts. Our allergist has requested tha we call him weekly to give him updates on the hives. (They cleared up immediately after we gave him the first dose of new medicine the allergist combined. It's been a week and the allergist is keeping him on the medicine.) Based on all of your experiences, is his allergy being handled the correct way? Like someone else said in this thread...I've learned more from all of you than my allergist.

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By Suzi-Q on Fri, 09-15-00, 13:04

My son has just been diagnosed with PA. He had one reaction at 1 yr. old and at 18 mos. was suffering from chronic hives. We took him to an allergist for the hives and hed him tested for 17 allergies. PA was the only positive result. The allergist did the scratch test on him, and said that we would watch him and decide later if we would perform the "blood tests." We carry an EpiPen and keep him away from peanuts. Our allergist has requested tha we call him weekly to give him updates on the hives. (They cleared up immediately after we gave him the first dose of new medicine the allergist combined. It's been a week and the allergist is keeping him on the medicine.) Based on all of your experiences, is his allergy being handled the correct way? Like someone else said in this thread...I've learned more from all of you than my allergist.

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By bboehm on Fri, 09-15-00, 15:28


I am familiar with the format your doctor gave you (.58). My son's last result was .42, conv. level I. (and 111 on the modified scale and modified level 2 if I remember correctly). I break down the lab's numbers in the "peanut allergy cure part II" thread.
This would be a low level allergy, however, it does not mean that your child will not react severly. Be safe.

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By cshames on Mon, 09-18-00, 14:25

Thanks for your specific reply to my question. The breakdown you give on the "cure - part II" is great. Do you know how that breakdown jibes with the other type of RAST scoring system (e.g. 751-1600 is class I, >18000 is class V)? Curious how to translate .58 there. Good news that your child's RAST results have fallen. The "Is my son really allergic?" thread on this board gives me hope in that regard.

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By tfl on Fri, 08-08-03, 04:44


[This message has been edited by deegann (edited August 31, 2005).]

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By [email protected] on Sat, 08-09-03, 04:14

I'd call the nurse back and find out exactly what test was done. Cap RAST has a different scale than the RAST. Then ask what category (such as 0-6) the resutls are. Sorry, but I can't give you any insight into the 270 number without more info. When does he return? That is awful for him to leave you hanging like this!


Mom to 2 y/o Karissa (PA >100 CAP RAST)

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By abbyuearq on Mon, 10-03-05, 19:12

Raising for JandEmom

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By momto4boys on Mon, 10-03-05, 19:35

Hello - I'm new here... and trying to figure out where my kids are at w/ re. to their PA.

My son is 5, has a level 3 allergy, and has had no reaction that we know of. He has severe excema, so any rash would be hard to identify specifically as a reaction to peanuts.

My daughter, 15 months, did have a reaction for the first time last week. She had peanut butter at her daycare, and immediately got hives all over. We took her in, had a blood test done and I just got the results. Level 4. Not sure what that means. We have a follow up appt scheduled in a couple weeks.

Does anyone know what this means. How to handle, etc. I'm freaked and any advice would be wonderful.


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