Her IgA was normal at 89. TTG IgA Ab was less than 1.

Thanks @trents I'll keep that in mind.

One thing to be aware of is that reactions to gluten can sometimes be more severe after having been gluten free for a significant period of time. Something to think about in connection with a gluten challenge.

Hi @trents Thanks for your reply and the clarification on terminology—most appreciated. My GP has referred us to a Paediatric Gastroenterologist, and we're waiting for an appointment. She mentioned they might want to do an endoscopy or run further testing. But that often with children they try to avoid scoping them.  She also said it could take months to get an appointment, which is why she recommended starting a gluten-free diet immediately to see if there's any improvement in his symptoms, growth, and blood tests. I have an appointment in 5 weeks with the Paediatrician (who ordered all the tests)—not the Gastroenterologist. I expect the Paediatrician will also recommend a Gastroenterologist referral for further testing and diagnosis. I understand the reasons for confirming with biopsies. I'm just eager to help him feel better and I don't want to keep him eating gluten for months while waiting for a specialist when it's clearly affecting him. I really appreciate your input on this, especially your thoughts about this pointing to celiac rather than NCGS. Intuitively, it feels that way—he's always been incredibly healthy and strong, but he's suddenly wasting away. We're in Australia, so I'm not sure about benefits, etc. and needing a formal diagnosis. I’ll have to investigate.  If necessary to do a gluten challenge down the track for confirmation I'm happy to cross that bridge when I come to it. Thanks so much for your advice!

Welcome to the forum, @cococo!  So. let me first clarify some terminology. Gluten intolerance is a general term that can refer either to celiac disease or NCGS (Non Celiac Gluten Sensitivity or "gluten sensitivity" for short). Having said that, in common, informal usage there is still a lot of mix up in the use of the terms "gluten sensitivity" and "gluten intolerance".  Elevated DGP-IGG can certainly indicate celiac disease but the IGG tests are considered not quite as specific for celiac disease as are the IGA tests, especially the TTG-IGA. If it were the TTG-IGA that gave a 250 score it would have been grounds for declaring an official diagnosis of celiac disease without further testing in the UK and many European countries. With children, however, because their immune systems are immature, we often see their celiac disease show up in the IGG tests rather than the IGA tests. Has their been any talk about an endoscopy with biopsy of the small bowel lining to confirm or disprove a diagnosis of celiac disease? The endoscopy/biopsy is considered the gold standard of celiac disease diagnosis. Physicians are not eager to do scoping on pediatric patients, however, and try to avoid that unless there is a very good reason for it.  I think to proceed with a gluten free diet experiment at this time is a reasonable approach. If there is improvement in labs, symptoms and growth then it is reasonable to assume that there is celiac disease to blame or at least NCGS. At the end of the day, both conditions require a gluten free diet anyway. But I would also have to say that when looking at the total body of evidence you present, it looks much more like celiac disease than NCGS.  One caution, however, and that is if you are in the UK there are certain government provided benefits that incur from a formal diagnosis of celiac disease. I mention that because some of your spelling suggests that to me.