January 14, 2013

Callan's peanut challenge

My first time buying peanut butter in nearly 8 years.

Last week I took Callan in for his first ever peanut challenge.  Our allergist suggested that chances were good that Callan is not allergic to peanuts after evaluating his having no reaction to a skin test from December and his most recent blood test IgE results.  (The skin test was conducted right before his and Ryken's baked milk challenge.)  I had been operating under the assumption that Callan had peanut and tree nut allergies based on IgE blood tests from 2010 and 2011 with numbers pointing to a moderate allergy to peanuts (2.5 KU/L) and low or moderate level allergies to almost all tree nuts.

I had gotten comfortable with having my kids get tested via blood.  I am a numbers kind of a gal so I appreciate having concrete information and being able to compare numbers from year to year.  IgE scores also get categorized into severity levels and this made it a little easier to talk to people about the gravity of my kids' food allergies.  With the skin test, reactions are measured by (W) wheal size (that bump that develops) and (E) erythema or inflammation/redness that you can see developing under the skin.  It's hard for me to recall how one reaction looks from one year to another.  So for me it is nice to have these neat reports with blood IgE numbers and a key for reading the level of severity of the reaction, reports that I can easily pull up in our online records. 
On the left: Callan was scratched with peanuts and various
tree nuts in areas 1 through 7.  He did not have reactions. 
Upper left is the control histamine while the wheal
on the right is for baked milk.

So last month's skin testing showed a discrepancy between what the blood test and skin test each suggested.  Our allergist explained that each of the tests can help predict whether a person has an allergy but neither is 100 percent accurate all the time.  (A double blind placebo-controlled food challenge is the best way to determine a food allergy...but you don't want to dive into those until you're confident there will be no reaction!) So it is often good to have information from both types of tests to confirm or challenge the high chance of an allergy. There is a new method for evaluating a peanut allergy, the uKnow Peanut molecular test, which is gaining more buzz as a more accurate means of determining a true peanut allergy.  (Apparently those with birch or ragweed pollen allergies may test positive for peanuts!)  I haven't checked out the uKnow Peanut test but it sounds promising albeit expensive.

When the IgE values are higher, there is a greater chance that an allergic reaction will occur.  According to research, the IgE of different foods has varying predictive value for allergic reactions and because of this, you cannot read the IgE results in the same way.  For example, for eggs, a IgE value is 7 KU/L or greater is 95 percent predictive of an allergic reaction.  For peanuts, 100 percent of individuals with IgE blood test result of 14 KU/L and above would react to peanuts in a food challenge.  Individuals with a peanut IgE of 1KU/L have roughly a 50 percent chance of reacting in a food challenge.

So there is definitely a chance that there might not be a true allergy if you are testing at IgE levels that are lower than these highly-predictive, minimum values.  This was probably the case with Callan.

The Challenge
This was the first food challenge I had ever sat through.  Veteran food-allergy moms advised me to bring entertainment (paper, markers, books, and DVD player and videos were popular with my son) and snacks for after the food challenge when we would still be required to stay under a nurse's care for 2 hours for monitoring.

The food challenge was scheduled for 8:30am.  Challenges are conducted first thing in the morning and patients cannot eat beforehand.  This helps to ensure that (1) patients are hungry enough to eat the challenge food, (2) nothing has been eaten earlier in the day that might cause its own allergic reaction and confuse the results, and (3) it keeps the stomach empty thereby lowering the chance of asphyxiation in case the food challenge induces vomiting.

I brought in the product to be used in our challenge, a jar of peanut butter.  The allergist double-checked the brand to make sure it was not made in a facility that also processes tree nuts as that could muddle the results in case there was an allergic reaction to the peanut butter.  I haven't thought of this!  Thankfully our Skippy brand was given the green light.  However, the allergist mentioned that Planters' nut butters have possible cross-contamination issues.

Callan was given peanut butter on a pretzel stick, also provided by me and not new to his diet.  He was given increasing amounts of peanut butter every 10 minutes: 1/8 teaspoon, 1/4 teaspoon, 1/2 teaspoon, 1 teaspoon, 2 teaspoons, and finally 1 tablespoon.

At first Callan was reluctant to eat, scared that there might be a reaction that necessitated medication.  After some reassurance from me he cautiously took his first lick on peanut butter.  It was curious but not too foreign since sunflower seed butter was a familiar taste already.  After a minute of no itchiness and no rash, I could see Callan's body relax.  His mouth widened into a big smile and declared that he really liked peanut butter!  The rest of the challenge went just fine -- no reaction whatsoever.  Callan had passed the peanut challenge!

A relaxed Callan made some cards for preschool friends
while we waited out the post-eating observation period.

We had started the challenge a little after 8:30am.  By the time the six quantities of peanut butter were consumed and the 10-minute wait periods had expired, it was about 10am.  We had to stay in the challenge room until 12pm to make sure no delayed reaction set in (and none did).  These two hours were probably the hardest because we just stayed in the room.  We were given a choice to walk about the allergy office's hallways to stretch but besides that we were not allowed to leave.  We ate snacks, drew pictures, and then I finally busted out the DVD player to pass the time.

We met with the allergist after the 2-hour wait period who congratulated Callan on passing.  She advised me to give Callan a peanut product at least twice a week in order to keep peanuts in his system.  She said that research has shown that individuals with siblings with peanut allergies do have a higher chance of developing the allergy at some point.  Keeping up with exposure to peanuts can help protect Callan from (re)developing sensitivities down the road.

I was worried about how Ryken was accept the reality that his brother was not allergic to peanuts while he is still very much allergic.  For the days leading up to the food challenge, Ryken had been telling his adoring little brother, "If you can eat peanuts, I'll be allergic to you!!"  Words like these offered little encouragement to Callan and, not surprising, he did not want to take the peanut challenge.  The morning of the challenge I took Ryken aside for a talk.  I looked him right in the eyes and told him that, while Callan would be under a doctor's care and that his skin tests showed he had good chance of not being allergic to peanuts, a food challenge still was a little dangerous.  I needed him to hope for the best for Callan and give him confidence to take this test.  I promised Ryken that I am always looking out for both of my boys' safety -- Callan's at his food challenge and Ryken's if Callan should pass and need to eat peanuts to protect him.  Ryken looked at me and clearly understood.  He got into big brother mode and has been positive since finding out that Callan passed.

So now my newest task is figuring out when to give Callan peanuts (I'm sticking with peanut butter) and how to ensure that his peanut-allergic brother remains safe.  I might have them use separate toothpastes and designate one special "peanut butter spoon" to always use for Callan to reduce the chance of accidental contact.  There are some details to work out but I am more than happy to have this problem!


  1. I am amazed by the resilience of both you and Callan. The challenge it seems comes not only physically, but through the emotional stamina that you have endured together. This is most certainly another bittersweet journey for this mother and son to keep close to their hearts.

  2. This is great news, and good luck with the reintroduction of peanuts. We're seeing our allergist tomorrow and may have a food challenge in the near future (?). Very helpful hearing about your experiences. Thanks!