--for neurological symptoms to be a presenting symptom of autoimmune reaction to gluten.

Peripheral neuropathy is one of these (gluten ataxia and seizures are others), and it is prevalent enough that the researchers who have done the work in this area (mostly Latov,Chin, Green, Fasano and Alessio in the US, and most importantly, Hadijvassiliou in Finland) recommend a test for the antibodies in anyone with an otherwise unexplained neuropathy. In fact, there is some evidence that people who present first with neurological symptoms may have a different genetic profile than the "typical" celiac who presents with gastrointestinal issues (the Gluten File details Hadijvassiliou's work in this area).

There are no appreciable villi in the large intestine--was the colonoscopy otherwise unremarkable? (I just had a screening one--no polyps or inflammation found, so I'm good for five years.)

The thyroid issues can make you feel tired/lethargic by themselves. There is a tendency for people with one autoimmune issue to have others, though, so if there is evidence of autoimmunity to the thyroid (with the antibody markers) that's another reason to get the gluten/celiac testing (there are numerous people with both).