And in many cases it's also necessary to provoke the problem in order to test properly. I've been on a gluten free diet for ten years (my skin kept falling off,

And in many cases it's also necessary to provoke the problem in order to test properly. I've been on a gluten free diet for ten years (my skin kept falling off, stopped when I quit gluten, father had celiac) and always test negative because I won't gorge on gluten for the two weeks necessary for antibodies to show up (simply as I don't have a month spare to be ill).