Thanks for your reply, Fiveworlds.
I see your perspective on relating metabolic processes but simply put, if patient X has adverse reactions to gluten, perhaps not at the level of a celiac, but nevertheless adverse, and patient X also has a history of Alopecia Areata, then how is gluten causing the patchy hairloss?
My current theory is this, and please correct me if you think this is inaccurate:
The gluten antigen is similar in homology in its protein sequence to the antigen that causes Alopecia Areata. The resultant would be the body responding to one signal, in two ways; people that do not have issues with gluten can still have Alopecia Areata because of the antigen but would not have the characteristics of a celiac.
My other theory is simply that the adverse reaction to gluten results in destruction of vital cells in the intestines that would normally be involved in nutrient absorption that are critical to hair, such as biotin; this theory would make sense but alopecia areata is an autoimmune condition, making it a bit difficult since the autoimmune response would be in response to a specific trigger, not the lack of nutrients.
My last theory is what you had mentioned, metabolic processes. However, based off of theory 2, this does not make sense because alopecia areata is autoimmune. In essence, we have two autoimmune diseases and they may have a common cause: gluten. If this is so, why is gluten causing two autoimmune reactions? Is it because the antigens share homology and thus activate both autoimmune disease pathways OR is it because the gluten antigen simply activates two pathways (which wouldn't make sense unless the antigen sequence was similar among the two completely separate diseases)?
I've been pondering this for a while and must find the source!