Yep - I have been tested for that by my old GI when he was trying to determine if I had Celiac along with the lovely Crohn's. He did so many in depth tests trying to determine what felt like EVERYTHING. Thankfully no celiac, but just Gluten Intolerance, Lupus and Crohn's.
My level was deficient also. I have definitely felt much better with NO Gluten (i.e. wheat and it's not so lovely derivitives) And what is even more interesting is that my daughter who has severe Eczema has tested allergic to Wheat, rye, gluten, and dairy - which are all big AI triggers. We have seen a HUGE improvement in her symptoms since we put her on a Gluten Free, Corn Free and Dairy diet. So I would not be surprised that she isn't deficient too, especially since I believe it tends to run in families and also in European decent - which my hubby is.
Your endoscopy with biopsy will be the best diagnosis - but I am one that still feels (after much research) that anyone that has any type of AI Disease should try going Gluten free for a few months and see how they feel after about 6 weeks. Just my 2 cents.
HTH