Welcome to my blog!

This blog is a journal of our struggles with food allergies and eosinophilic gastrointestinal diseases (EGIDs). ("DD" stands for "dear daughter", so whenever you see it in the blog it is referring to my daughter and our personal experience.) My hope is for this blog to be a source of information and support to others who might be trying to investigate, diagnose, treat, or live with, food allergies and EGIDs. Feel free to leave comments with suggestions or requests of what you would like to see on this blog. This is a work in progress. :)

Atopy Patch Testing (APT)

Atopy patch testing (APT) is done to diagnose non-IgE, or delayed reaction, allergies.  Many allergists don't do this test, or even believe that it works.

According to the most recent AGA paper on eosinophilic disorders:
  • "APT has been most extensively studied in atopic dermatitis. Most studies find that APT was better in identifying late reactions and GI reactions in children with atopic dermatitis."
  • "...APT has shown promise in atopic dermatitis with good predictive values, high specificity, and low sensitivity, and APT has shown highly promising results with regard to food elimination diet and food reintroduction in patients with EE."
  • "APT has been used for the diagnosis of food allergies in two published studies by Spergel et al. They examined 146 children with biopsy specimen-diagnosed EE and eliminated foods based on positive skin test and atopy patch test. The authors found that 77% of the patients had resolution of their biopsy specimens based on these results."
Basically, by using APT in conjunction with SPT (skin prick testing), greater improvements were seen in kids with eosinophilic disorders (and kids with food allergies and/or eczema.)

We searched and searched, and finally found a local doctor that does patch testing and regularly works with eos kids.   Here's how it works:

  • First, foods are crushed up and made into a thick paste that will stick on the skin (and not dry out.)  Some doctors use food extracts, but from what I've read the accuracy is much higher when using real, fresh food.
  • The foods are placed into small round or square disks that will be applied to the back for 48 hours, and taped into place.  The doctor carefully marks where each section is, so that they are easy to identify when the tape is removed. 

  • After 48 hours, the patches are removed.  Some doctors will read the results 20 minutes after removal, but it's really hard to see much at that point since the skin is usually still red from the tape.
  • Here is DD about 5-6 hours after removal.  It's getting much easier to see the spots that she's reacting to (which is almost all of them!)  Negatives should be skin colored, positives will be red and possibly blistered or have hives.  (Our allergist made sure to do skin testing first, because applying an IgE allergen to the skin for 48 hours would result in a massive and unpleasant reaction.  So they only test foods that are negative on the SPT.) 

  • 24 hours after removal, the patches are read.  You can see that by this point, many of the spots on DD's back had faded, but some are still obviously positive.  The positive spots were still red, and most were bubbly and irritated and starting to scab over.


Delynn said...

I find it amazing to see someone else struggling much like we have. My son just turned 3 and was dx with egid he was just over a year old. He's been on Neocate JR formula as he main source of calories since. We have gone through all the same testing, he tested positive to everything but green beens potato and lamb. We have slowly started adding more food back and going in for biopsy like every 6 wks. I thought we were done, but after his last biopsy in Jan he has been as sick as he was before. refuses food. Hes been in for IV fluids at least twice. His PCP is talking to his GI this week to find out where we go next. I'm a tired, frustrated mom. Here's hoping we both get some answers soon. But i wanted to let u know about the formula. It has definitely help him gain some weight back and keep it on. =)

Jessica said...

Oh, I'm so sorry to hear that Delynn. :( It's not fair that these kids have to struggle like this. I hope you find some answers soon!

Anonymous said...

I am currently trying to find a doctor that will do this test to my daughter and have no luck. What kind of doctor finally agreed to it, was it an allergist?

Jessica said...

We had it done by an allergist, but it took months of phone calls to find one that would patch test for foods, AND he will only do it for children diagnosed with an EGID.

I hope you can find someone!