Negative CAP Rast Test - Previously level II


Has anyone had a negative CAP Rast test and if so, what was done and what was the outcome? At two my son had a level II on the CAP Rast - Now at 4, his result was negative. We have learned a great deal about the peanut allergy and are not ready to let down our guard. While we are very thankful, we hesitate to challenge him for the fear that he may still have a reaction and/or resensitizing him to the allergen. In addition at the age of 4, he is not accepting of any unusual foods - he spits out just about anything different from his day to day diet.

We are considering having him retested in a year or two and then think about a challenge.

[This message has been edited by Jim (edited August 05, 1999).]

On Aug 6, 1999


Our son's allergist suggested that if both the skin test and CAP RAST test were negative to then possibly try a food challenge as the only means to be sure he still has the allergy. Has your son had a skin prick test? Because Tanner's skin test is still positive and he has had a clinical reaction, we haven't had the CAP RAST test. His allergist plans to do another skin test next year (at 6 yrs old). Mark

On Aug 6, 1999

Jim, Our son's first and only CAP RAST came back negative two years after a reaction and positive skin test. We repeated the skin test and it came back positive so we did not do a food challenge. Our allergist will repeat the skin test before he enters school and would do a food challenge only after two negative skin tests. Good luck and keep us posted!

------------------ Valerie

On Aug 6, 1999

Jim: I too would suggest the skin prick test. That, to me, is the deciding factor. Also, you may want to check with FAN or Dr. Hugh Sampson regarding the likelihood of outgrowing a PA. It was my understanding from Dr. Sampson that this is not an allergy people "outgrow". However, the July Women's Day magazine had a good article on the difference between food intolerances vs. food allergy. Did he ever actually have any severe reactions to the peanuts, or was the testing part of an overall allergy test? I think you are correct in remaining cautious; you may also want to get a second opinion from an allergist who specializes in food allergies. Good Luck! Michele

On Aug 6, 1999

Thanks everyone for the feedback. After exploring further, I found the June/July 1998 FAN newsletter with Dr. Sampson writing a column about the British study of some children outgrowing the peanut allergy. Some of the recommendations made in the article were: Waiting at least 3 years after the last reaction for further re-evaluation which would include determining the level of peanut-specific IgE Antibody with a CAP systems test; IF a CAP test is negative, a skin test should be done - If both are negative, consideration may be made for a challenge, depending on the child's history.

To answer some questions, my son did test positive both in skin and CAP Rast. His reaction were hives around his eye and his eye white turned red after holding a pb sandwich. We will be waiting for a couple of more years and will have him retested with both the CAP and skin tests before considering a challenge. Again, thanks for the feedback!

[This message has been edited by Jim (edited August 06, 1999).]

On Aug 6, 1999

Hi everyone,

What does this all this really mean? How can you have a positive skin test and a negative CAP RAST, or vice versa? I am really confused now - guess I need to explore this with the allergist. My son has only had the skin test (showed a HUGE reaction there) and my allergist never even offered the CAP RAST.

Stay Safe, Debbie

On Aug 6, 1999

Hi Debbie:

All the allergy tests: CAP RAST, RAST, and Skin Prick Tests have their strengths and weaknesses and all are fallible. That's why allergists believe oral challenges are the only way in which they can determine with absolute certainty whether an allergy has been outgrown or not.

Allergies can be outgrown. Just because someone outgrows a peanut allergy doesn't mean they've had a food intolerance all along. There's a wide spectrum between people who have allergic reactions to peanuts and the 6% who have anaphylactic reactions. Now, it is true: once you've crossed that line by having a truly severe reaction to peanuts, then your chances of outgrowing the allergy is extremely rare.

Jim, I think your son has a good chance of outgrowing his peanut allergy based on your description of his only reaction and his test results. I wish you all the luck in the world with God's grace in putting this allergy behind you.