<<Disclaimer: Verify this information before applying it to your situation.>> Dear Ethan: An IgA Tissue Transglutaminase (tTG) Autoantibody Assay, such as our at-home test known as the cdSCAN, is designed to determine if gluten-reactive individuals have celiac disease. After an elimination period (100% gluten-free), the antibody associated with celiac disease may not be detectable, thus ANY laboratory's IgA tTG test, as well as an endoscopy, might report that an individual is negative for celiac disease - when in fact they actually have it (celiac disease). If whoever you are thinking of requesting the test for has consumed gluten and/or gluten-contain grains in recent history, then the IgA tTG antibody levels should still be ele vated - as long as they truly have celiac disease. Also, in case you are thinking about doing a gluten challenge, I would recommend against it as this is a bit of a clouded area where there really are no good answers. Some individuals develop elevated levels of the IgA to tTG antibodies very quickly after starting a gluten challenge while it might take others more time to do. One thing you could do just to make sure, is to be screened for food intolerance and see if there is a current positive reaction to gluten and/or gluten-containing grains. Our foodSCAN 113-food panel not only screens various gluten-containing grains for IgG-mediated food allergy, but gluten (gliadin) intolerance as well. In the event you have been living a gluten-free lifestyle, but are still experiencing ill-health, you may likely be suffering from IgG-mediated food allergy to foods other than gluten. I hope this information is of b enefit. Please let me know if our office may be of any further assistance. Sincerely, John Kernohan, Director York Nutritional Laboratories, Inc. 2700 North 29th Avenue, Suite # 205 Hollywood, Florida 33020 USA Toll Free: (888) 751-3388 Tel: (954) 920-3728 Fax: (954) 920-3729 mailto:[log in to unmask] http://www.yorkallergyusa.com "Optimum health is at the tip of your finger..." *Support summarization of posts, reply to the SENDER not the CELIAC List*