when to test younger sibling


Hi everyone, I have a question about my daughter. My son, who is now 5, and has been PA since 10 months of age. My daughter is 2 1/2, and we have been treating her as if she is also PA. We have never had her tested, and I am just wandering, are we supposed to wait till she is 4? And, if she has never tasted peanuts, will she show as a false positive? Should I have her take a taste challenge test? I am just preparing for what to do at this point. Thanks again for any input. Amy

On Dec 5, 2002

Amy- We skin tested our younger kids when it became likely that they might be accidentally exposed to peanut (i.e. before they started Sunday School) at age 36 months. Luckily they were negative. I wouldn't worry about false positives (meaning the test is positive but your child is not actually allergic) if your child has never been exposed, but it is possible (but unlikely) that you could get a false negative result. That is, the test is negative but your child is actually allergic and reacts when exposed to peanut. We were told that the skin test is highly sensitive, that is, if the test is negative, it is very unlikely that the child is allergic. It is also possible to have a positive test if your child has never been exposed to peanut. This would not be considered a false positive. Despite their negative tests, our younger kids have never been exposed to peanuts or tree nuts or "may contains". I don't know when we'll have the nerve to let them eat peanut or tree nut...probably before they start kindergarten (although our school is peanut-free). HTH.

On Dec 5, 2002

My first two kids are PA... my 3rd child has never had anything with peanuts. We treat him as if he was pa too He will be tested when he's 3. My allergist feels if he reacts positive to the skin test, that is not conclusive that he is allergic. He will want to do a food challenge to be sure. Fortunately, the hospital is right across the street from his office so I may agree to do this. Plus, this doc knows how sensitive my girls are so I am confident he won't give Jackson a tbl of peanut butter!

On Dec 6, 2002

This question has been asked before, so if you'll do a search, you'll find more opinions to help you out.

I am of the 'school' that believes someone cannot test allergic to something he's never been exposed to. The body needs at least one exposure to build up the antibodies that react to it.

That said, our youngest is 4 and hasn't eaten any P/TN products, and wasn't exposed in utero or through nursing. He was tested a couple years ago, only because he was having difficulty eating - we later found out he has oral motor problems. He tested negative - I'm not surprised. We don't consider him "not allergic" though. We won't feel sure of that until he's been exposed (eaten something P/TNutty) at least once, then tested again. This will have to be done before he enters preschool or Kindergarten.


On Dec 6, 2002

Lam...your theory seems right for my DS. My son recently had an anaphylaxic reaction to Kiwi (he also is allergic to nuts) and we were shocked since he had safely eaten kiwi one other time.

On Dec 6, 2002

My PA and TNA son ate handfuls of cashews the first time. The second time he ate four small pieces and had an anaphylactic reaction. I don't recall it being the same for peanuts though.

On Dec 6, 2002

Hi Amy. I know this is a little off topic, but I thought I'd share with you my experience in the hopes that you might learn from my error.

When my younger daughter was allergy tested at age 4, I combined that appointment with one for my older daughter's check up with the same allergist. I often will bring both girls in to the pediatrician or dentist at the same time (or back-to-back appointments) just as a time-saving convenience for myself.

It was a bad situation to have both children there. The experience was traumatic to my older (8 years old) PA daughter. After a second negative skin test to peanut, the allergist wanted to give her a challenge. My older daughter freaked out and begged me not to let the doctor give her little sister any peanut butter. It was very sad to see her so frantic and trying to protect her sister. It took her a long time to deal with it all. Very trumatizing.

Just a word of warning that you might want to schedule an appointment for only your child who is being tested.


On Dec 6, 2002

What about my last child? He has never eaten peanuts, but was exposed through breastmilk. I remember eating an apple with PB and raisins on it while breastfeeding him at 5 mos. (right before other son had a positive skin test). So theoretically he was exposed, but not through him actually eating PB or something with peanuts in it. He'll be getting a skin test and blood test. He'll be tested next summer after he turns 4.

On Dec 6, 2002

Hi Amy2. My allergist, Dr. Wood at Johns Hopkins, has advised us to have our daughter tested when she turns 3. He will do a CAP-RAST test on her at that time. I asked him if a test could really show if she's allergic since (we hope) she's never been exposed. He said that prior exposure is not necessary -- that a CAP-RAST would indicate if she was allergic as long as she is at least 3 years old (prior to that age, such a test would be meaningless). I have the utmost faith and confidence in Dr. Wood's medical opinion.

You might also be interested in knowing that Dr. Wood told us that if our youngest absolutely avoided all peanuts (and tree nuts for that matter) -- this means all trace amounts, peanuts during pregnancy, breastfeeding, etc), that our youngest one's chances of developing a peanut allergy would be less than 1%.

Good luck.

On Dec 6, 2002

My daughter 5 years is allergic to peanuts and will be retested in February, at the same time my son 3 years will be tested for Bee stings as well as peanuts. He has never been tested before for either bee stings or peanuts. He has already had severe reactions to bee stings so we just assume that he is allergic regardless of the testing. But we do not have an epipen for him which is something I want. I plan on exposing him sometime over the christmas holidays to peanuts. Our previous allergist had suggested he be exposed before the testing.

On Dec 8, 2002

I had my daughter allergy tested, and specifically for PA when she was 3 years old so I would presumably know if she was PA before she entered the school system. Her skin prick test came back negative. The allergist concluded that she was not PA.

However, I did post the results of both her's and Jesse's allergy testing here at the time it was done and you know what? I really don't know if Ember is PA or not. Why? Because she has never been exposed to a peanut product except on rare occasions in utero.

Because I found out Jesse was PA when I was 7 months prego with Ember, she has never eaten a peanut product or even a "may contain" product. She is *allowed* at school, should a baked good come in for the class to share to eat what may be a "may contain" product. She is not allowed to eat products that are brought in labeled "may contain" and last year we did provide her with a special treat box should something like this happen (which it did).

Bottom line - I don't know if Ember is PA or not because I would not consider her limited in utero (that looks wrong [img]http://uumor.pair.com/nutalle2/peanutallergy/confused.gif[/img] ) exposure to actually be exposure to a peanut product.

She is treated as though she is PA at home. I actually don't want her eating any peanut products anyway because of the potential risk to her brother (she is still the messiest eater I have ever seen).

Should she somehow be exposed and react, obviously we are prepared with our Epi-pens and antihistamines (and asthma puffers).

I strongly feel that she isn't PA. Call it just gut instinct.

Only should she have some type of reaction at school would I consider having her re-tested or first exposed *properly* and then tested.

Not much help at all. I'm sorry. [img]http://uumor.pair.com/nutalle2/peanutallergy/frown.gif[/img]

Best wishes! [img]http://uumor.pair.com/nutalle2/peanutallergy/smile.gif[/img]


On Dec 9, 2002

You know, I just never know whether or not to trust my allergist and this just causes me more concern! I asked my PA son's allergist about testing my second child (who is only 6 months right now) and he said he would only test him if he had a reaction. This allergist never does RAST testing either. Should I be getting concerned?

On Dec 9, 2002

Hi Jody -- Just my opinion, but I think you have good reason to be concerned. Before I began taking my daughter to Dr. Wood at Johns Hopkins, I thought that as long as my DD was seen by a board certified pediatric allergist, we would be fine. I was wrong. Fortunately I had done quite a bit of research on PA before my DD's first appt. I had read about how skin tests yield a significant number of false positives and false negatives, how 20% can outgrow PA, etc. When I questioned this first allergist about this, he told me I was totally wrong. Children never outgrow PA and there are no false positives or negatives associated with prick tests. He basically disputed what all the latest research at the time was supporting. I concluded that he was one of those doctors who does not keep up with the research and just practices the way he always had for the past 20 years.

Upon recommendation, I took my daughter to Dr. Wood. Although it's quite a drive, it's been well worth it to know that I can consult with an allergist who knows what is going on (at least as much as is possible!) in this constantly changing field of food allergy.

If you haven't done so already, I would read some of the lastest findings in food allergy printed in the medical journals and question your doctor about them. I would also question his sole reliance on prick tests. (Dr. Wood says they're almost worthless.) If your doctor can't give you satisfactory answers, I would try to find someone who can.

Good luck.

[This message has been edited by Kami's Mom (edited December 09, 2002).]

On Dec 10, 2002

Kami's Mom- Dr. Wood said prick tests are almost worthless? I'm going to have to call him today to ask about this. He advised us to have our younger kids skin tested to rule out food allergies. We did so and they were negative. Do these results mean nothing?

On Dec 10, 2002

BS312 -- It's been my understanding from seeing Dr. Wood for the past two years that skin testing is not very reliable. I would never want to mislead anyone as to his views on skin testing, so I'll just quote from a paper he presented at the FAAN conference last March in Baltimore:

"The problem with allergy testing, however, is that there are a large number of inaccurate results from both skin testing and blood testing. While it is possible to have a negative test in an allergic person, it is far more likely to have a positive test in a person without true allergy. There are two main reasons for these false positives tests. First, it is possible to have enough allergy (IgE antibody) to produce a positive allergy test but stil be able to eat that food without difficulty. Second, when you are truly allergic to one food, it is common to have positive tests to other related foods. Examples include positive tests to soy and other legumes in peanut allergic patients or a positive test to been in milk allergic patients. It turns out that over 50% of all positive allergy tests are falsely positive..."

Another problem that Dr. Wood cites is that once an allergy has been outgrown, skin tests may still remain positive.

Therefore, he states, "We have come to rely more and more over the past few years on RAST tests and less on skin tests. The RAST test measures the level of IGE antibody for a specific allergen in the blood. A newer version of this test, called the CAP-RAST, has proven particularly useful in helping to sort out true allergies from false positive tests..."

I don't understand why Dr. Wood recommended skin testing for your kids but not for mine. Based on my conversations with him, the CAP-RAST is the gold standard. Maybe I'm missing something, but it would seem to me that since there are instances where skin testing is unreliable, why do it at all? I'm curious as to what his response is.

On Dec 11, 2002

Kami's Mom- Thanks so much for your thoughtful reply to my post! My DH spoke with Dr. Wood's nurse practitioner yesterday. It seems that they sometimes use prick tests to screen for PA because the test is very sensitive and false negatives are unlikely. The test is less useful when it is positive, because it could be a false positive. Dr. Wood's hand-outs from the FAAN conference are great. I have given them to school staff to help with education. By the way, did you see the Taste section from the Baltimore Sun today? There's a gross article about a peanut company.

On Dec 11, 2002

BS312 - I must be psychic. Just went to check the discussion boards and it looks like you just posted.

Your response makes sense, but I'm still confused as to why a CAP-RAST was recommended for when my youngest turns 3. I guess I'll just ask for myself.

No, didn't see the Sun article. (We live outide of DC and get the Post). I'll see if it's online.

Nice chatting. Take care!

On Dec 12, 2002

So, are you guys saying that if my son has only tested PA positive on a skin test I should insist on the Rast testing to confirm he is truly allergic? I know he had the allergy as he had a reaction when he was 18 months. He was recently re-tested via skin test at 4 1/2 and it was still positive. I am assuming he didn't outgrow it. Could this be wrong?

On Dec 12, 2002

Jodi- Yes and yes. Dr. Wood did not follow skin tests once my DD was known to have the allergy because the skin test can stay positive after the allergy is outgrown. He checks CAP-RASTs periodically and if the number is low enough he will consider doing a challenge in which she will actually eat the food (starting with a tiny amount) in his office. For example, she had a known milk allergy. Her milk CAP-RAST was very low last summer. She had one teaspoon of milk in the office and within two minutes had hives on her face, and later vomiting. She is still allergic to milk. He recommended waiting two years before checking her milk CAP-RAST again. Peanut allergy would be handled similarly. HTH.