Low iga results and aed

We are in process of testing my profound autistic, epileptic daughter, 50 yrs old, for probable celiac disease, my research shows a low iga( hers under 15,normal 87 - 484) can be caused by some aeds and her lamictal one of them,also dilantin she took previously
We can't get positive celiac diagnosis without a endoscopic biopsy so trying to figure out if her drugs may have damaged her small intestine?
Hope to post on gi support group also.Very hard to change her meds ..
Thanks