Increased intestinal permeability can represent compromise of the epithelium's integrity and is thought to be the primary mechanism in patients who develop Celiac Disease (CeD) and non-celiac gluten sensitivity when gluten peptides cross the barrier and trigger an immune response. In this study, the investigators propose to use a novel, minimally invasive technology to detect mucosal damage (i.e. barrier dysfunction) in the duodenal epithelium. The primary aim of this study is to identify if there is a difference in duodenal mucosal impedance between CeD and control patients.

Inclusion Criteria:

• scheduled for endoscopy as part of routine care with or without suspected Celiac Disease based upon at least 1 positive serologic marker of CeD
• consuming gluten at time of endoscopy

Exclusion Criteria:

• Already on a gluten free diet or unwilling to undergo a gluten challenge
• Undergoing upper endoscopy for an urgent indication such as unstable gastrointestinal bleed or food impaction
• Patients with inflammatory bowel disease
• Patients on blood thinners other than aspirin at time of endoscopy
• Patient unable to give informed consent
• Patient less than 18 years old

Celiac disease patients will be identified in the Celiac Disease Clinic at Vanderbilt. Patients will be asked if they would like to participate in the study during their clinic visit and will undergo consent for the study at the time of procedure. Control subjects will be asked about participation at the time of routine endoscopy.