I see this is an old thread, but I googled for info re: same subject and then found this link, so I thought I'd add it in case it might steer someone else (and you):
http://www.clinchem....t/42/7/1064.pdf . A friend had high IGA on her negative celiac panel (hence my googling around) and she has blood sugar issues, likely gastroparesis (she is not heavy, but does seize when eating too much fruit - she also likes her desserts, but I've only heard her say her gut seizes with fruit). I know her A1C was 5.4 on same lab; I don't know if she tests her blood sugars. She might be hypoglycemic as I've heard her wonder aloud.
Also, I agree with Ursa Major re: dairy. Dairy, grains and meat are acidic. To gain bone strength one should eat more alkaline foods: GREENS, veggies and fruit. I'm not saying to discontinue any food, to just eat double or more of the alkaline.
P.S. I also found these re: ankylosing spondylitis http://bit.ly/cpGzsG (& from google search http://bit.ly/da6IQn ): http://ard.bmj.com/c.../3/180.abstract , http://www.kickas.or...as9/index.html.
...and come to think of it, re the friend I spoke about earlier? She has severe bone problems, the nature of which (dx) I couldn't really comment; just to say she had multiple surgeries to correct her legs/feet when she was a child; and she currently complains of lower back pain. Conjecture at this point. (I don't seem to know how to post yet, forgive me.)