Here is a link to a podcast from American College of Gastroenterology regarding diagnosis and management of Celiac disease.
At about 9:00 they start talking about diagnostic protocols, including blood testing, when to do endoscopy, and how to manage patients when serology and histology disagree.
At about 14:30 discussion of gluten challenge including when to do a gluten challenge, and what the patient should do.
21:53 Discussion of clinical trial evaluating gluten challenge and how it best works.
24:53 Follow up guidelines for those diagnosed with Celiac.