Inclusion Criteria:

• Patients will be identified as direct referrals to the general GI clinic, the general medical clinic, or the motility clinic. Referring providers will also be notified of active research trials in the Division of Gastroenterology, and this study will be highlighted.
• Patients will be scheduled for a screening examination. Symptoms will be assessed and patients categorized into either the PDS, EPS or mixed subtype.

Exclusion Criteria:

• Patients will be excluded from the study if symptoms are thought to represent an organic disorder (e.g., peptic ulcer disease, hepatitis, pancreatitis, inflammatory bowel disease, type I diabetes, a known malignancy, radiation-induced injury, an active infection, vasculitis, celiac disease), or if the patients have known GERD, esophagitis, eosinophilic esophagitis or H. pylori.
• Patients with prior surgery to the esophagus, stomach or duodenum will be excluded, as will those on opioids, steroids, anti-histamines, immunosuppressive agents, NSAIDs, or mast cell stabilizing agents within the prior 3 months.  
• Patients will be asked to remain off PPIs and aspirin products for 4 weeks prior to testing.
• Alcohol and tobacco use will be assessed as will the presence of atopic conditions (eczema, allergic rhinitis, asthma).
• Patients will be questioned about possible inciting events to determine possible etiologies for dyspepsia. Patients with co-existing IBS will be allowed to enter the study as long as symptoms are not predominant.