<<Disclaimer: Verify this information before applying it to your situation.>>

A biopsy shows tissue damage caused by gluten reaction. Therefore if one
is on a strict diet the biopsy will show no tissue damage. This is good for
follow ups to check for both adherence to the diet and to see if there is
the rare occurrence of continued damage even while on a gluten free diet.
However, the biopsy is not a good diagnostic tool to establish the
existence of celiac disease IF the gluten free diet has been already
started for over six months. In these cases, from what I understand, a
gluten challenge would be required.

 How does the ELISA test based on tTG (tissue Transglutaminase) compare in
diagnosing celiac after the diet has already been started and as a follow
up to confirm diet compliance?

 The tissue Transglutaminase test is much more attractive as it is a simple
blood test and more importantly it is not subject to misinterpretation by
the lab technician reading the biopsy slides. I imagine that this
misreading occurs frequently, as the North American medical community view
celiac disease as a rare disorder and therefore do not have much experience
interpreting the results.

Thanks for any info.