In both senerios - hypothyroid and adrenal distress - gluten is bad. You may want to pick up Dr. Wilson's adrenal fatigue book and read about the dietary advice he shares - ( you may be able to Google that too)
You may also want to look over some iodine information on deficiencies too. Alot of information is our there on iodine deficient American's and allergies that can be link to this mineral.
You think we are plentiful in iodine - but truth is - we are not by all means and these types of reactions and "stress" can be linked together.
It sounds to me like the reaction you have to food containing gluten involves an overactive response by your adrenal system (the anger, the pounding heart). Gluten allergies can affect the body in so many ways--rashes, mouth ulcers, calcifications. I get hypothyroid when I eat too much of any grain, or eggs, or dairy, often in a matter of minutes, and then I have delayed reactions--acne, migraines, night sweats--for a day or two afterwards.
I know it's really hard to give up wheat--I put off thinking about it, but then my kids turned out to be allergic to gluten and we made the house gluten-free. After a while it gets easier, and you know you will feel better. It is definitely a bummer not to have support from your doctor. In my experience, you have to trust your own reactions to foods even when the official medical tests show nothing is wrong. You know your body and how you react. You wouldn't make up something so unpleasant.
Even if your panels come back negative you could still have a gluten intolerance and if it eliminating it from your diet helps you should continue on that way. Good luck.
I have coeliac disease and the symptoms I experience are really bad stomach cramps, diarrhoea, sometimes vomiting, tiredness, if I don't stick to the diet weight loss and spotty skin.
Hope this helps.
Not everyone will have the same allergic reactions/symptoms to gluten.
For instance, you mention the diarrhea. Some individuals will experience diarrhea, constipation, or a combination of both.
If eliminating gluten from your diet makes you feel better, then by all means stick to a gluten-free diet.
Meanwhile, you can always get a second opinion and/or see a specialist, if you haven't already.