Celiac or something else? Long post! Lots of tests!

geneva75, Since he has vitamin deficiences, have they checked him for SIBO? SIBO can cause that. It's a simple taste.

Praying for your son and you. I am so sorry he is battling this. Blessings.....

I do have celiac. Endoscopy done villia all flattened upper GI. Blood test were positive for celiac. IgA very high. Bloating diarrhea common. Switched to gluten free. Better. There are many causes of stomach ailments besides celiac. Your on the right track with GI doctor.

geneva75, Correction....It's a simple TEST. Sorry for the typo.

Very hard to not worry. My wife has 9 gi conditions! Gerd, so lessions, chronic, hyatil hernia and more. 25 years of managing issues. Small meals, Align prebiotic, mantoprazole and several others. We have learned through trial and error it comes down to 2 things. The doctors treatments and food/meds combination. 2nd, 3rd and 4th opinions if nec to be sure u have a correct diagnosis is a must. My wife is now with same gi doc for 20 yrs. Had a few cancer scares he got us through. You MUST GET DIAGNOSIS FOR EACH OR ALL ENCOMPENSING CODITIONS. Gi issues are a long haul, ur son needs support of doc to ensure faith in his treatment plan. You his home support and love value can not be underestimated. My wife cries at times for bringing this into our lives, big hug, tell her thank God we have a very smart doc. Get accustomed to praying for for improvement, it will help you. Patience, love, don't lose hope and push forward only way to go.

I get the runs from milk and eggs.
Have you had allergy testing for food.
It is the milk protein I don’t tolerate. Are the whites and eggs.
It is hard to deal with these two allergies. Egg whites is what makes bubbles and soaps and so on
A lot of medication’s contain egg and milk and them
There are other things I am sensitive to as well.
When I was intensive care having treatment, the only thing I had to eat or drink was one can of something that tasted terrible and I got the runs. And the nurses did run as I told him you have 5 to 10 seconds to get me on the commode. Then I got dial diagnostics I need it.
I wish you the best

I have celiac disease (15 years) and collagenous colitis (8 years); my duodenum and bloodwork tested normal, my colon had microscopic damage. The genetic test for celiac is sometimes used, but ~40% of the population has the HLA-DQ8 (me) or/and HLA-DQ2 gene, however, almost 100% of people with celiac have one or both. There is also the possibility gluten intolerance causing the inflammation. Since he has already had the celiac panel bloodwork, it might be useful to go gluten free for a few weeks and see if symptoms resolve; a registered nutritionist could evaluate his diet and see if an elimination or FODMAP type diet would be useful. Gluten is in many things (like soy sauce) so reading ingredients and controlling what and where to eat is important. Once I went GF it took several weeks for my GI problems to go away, my GERD, skin rashes, and enlarged lymph nodes in arm pits took a few months. I had a colitis flare this summer and ended up in Urgent Care because of Miralax (total blockage); fine now, but I've found other things my GI tract doesn't tolerate. If he has gluten or other food intolerance(s) life can return to normal once they are controlled.
https://www.nature.com/articles/modpathol2014135 https://celiac.org/about-celiac-disease/what-is-celiac-disease/

Immunoglobulin A is IGA so that is confusing. The anomaly in your post caught my eye, but I've not experience, so I'm just the fly in the soup.
H Pylori tests can be false negative. Often with adults H. Pylori cause slow digestion.
Gastric IM is a common of result of gastric atrophy.
Because he is going away at the end of summer, I'd ask for ANA antinuclear antibody testing. It can give false pos or neg and the significance is unclear requiring even more testing.
His timing is good. Excellent that you are pursuing it intently.
Best luck.

I was diagnosed with Celiac 15 years ago. Then 7 years ago I was diagnosed with Primary Immune Deficiency with low IgG and slightly low IgA. I went to an immunologist who did further testing to find out that I did not make antibodies to pneumococcus. There is a protocol the doctor follows to find out if your body is truly deficient and needs IgG replacement therapy, which I do. You need to find a good immunologist to do this testing. I don't know where you live, but I can give you the name of my immunologist in NJ if you like. Here is the important part: IF YOU HAVE AN IMMUNE DEFICIENCY IT CAN AFFECT YOUR GUT. The name of my immune deficiency is Common Variable Immune Deficiency (CVID) and it MIMICS CELIAC EVEN SHOWING A POSITIVE BIOPSY. 3 years ago I went to a GI doctor familiar with immune issues and he told me he didn't think I had Celiac. I did a gluten challenge and sure enough, I do not have Celiac. Steroids and or Plaquenil help with the celiac-type symptoms. I take predinisone and Plaquenil. I am feeling great eating gluten. Here is a YouTube link to a video about GI problems with immune deficiency. It's pretty technical: https://youtu.be/gtulxpP0CLE?si=2jm54Tj1Xb_tWI4-
Also, go to the Immune Deficiency Foundation website for more info on low IgG: https://primaryimmune.org
It is important to get any immune deficiencies addressed because it can cause inflammation and autoimmune disorders. I have Hashimoto's, lupus and sjogren's as a result of undiagnosed immune deficiency. Good luck with this frustrating journey.