Introduction: Some patients with upper gastrointestinal disorders have rapid gastric emptying. In patients who have not had prior surgery, the etiology of rapid gastric emptying is unclear. Patients with rapid GE may have rapid GE at one and/or two hours; whether these patterns represent different phenotypes, which are underpinned by different pathophysiological mechanisms is also unknown. Hence, our aims were to assess differences in the demographic and clinical features between patients with normal and rapid GE and separately among subtypes, defined by GE values, in patients with rapid gastric emptying.1212 Figure 1. Demographics and clinical featuresMethods: We reviewed the medical records of 6500 patients, aged 18 years or older in whom gastric emptying was evaluated with scintigraphy (296 kcal, regular fat meal) at Mayo Clinic, Rochester, and who authorized use of their medical records for research. Using sex—appropriate normal values, GE was classified as rapid if it was more than 5% above the upper limit of normal. Patients with rapid GE were categorized into 3 groups: rapid GE at 1 hour only, 2 hours only, or both. Results: After excluding 2660 patients who had major gastrointestinal operations (fundoplication, major intestinal and colonic resection), there were 3840 patients who had normal (2838), rapid GE at 1h only (464), 2h only (55) and or 1 and 2 h (483). Approximately 75% of patients in all groups were women and 40% were overweight or obese; the distribution of age, sex and BMI was not significantly different among groups. In addition to nausea and/or vomiting and diarrhea, between 48 and 67% of patients with rapid GE had constipation, which was more common (p<0.05) in patients with rapid GE at 2h than in the other 2 categories (Table 1). Between 42 and 47% patients had delayed colonic transit. Of various symptoms, anxiety and/or depression were more common (p<0.05) in rapid GE at 2hr, than in the other two categories. Conclusion: Approximately 26% of 3840 consecutive patients undergoing scintigraphy had rapid GE. The primary gastrointestinal symptoms were nausea and/or vomiting, dyspepsia, abdominal pain, heartburn, constipation and diarrhea. A substantial proportion of patients with rapid GE had constipation, not diarrhea, which is counterintuitive, but may be explained, at least partly, by activation of the ileal brake via rapid GE.