BACKGROUND/AIMS: In patients with neuroendocrine tumors, excessive production of serotonin and other amines may cause the carcinoid syndrome, which is mainly characterized by diarrhea and flushing. Little is known about the pathophysiology of carcinoid diarrhea. In several other groups of patients, diarrhea may be associated with rectal hypersensitivity and increased rectal tone. Therefore, the aim of the present study was to compare rectal sensitivity and compliance in patients with carcinoid diarrhea and in healthy subjects. METHODS: Twelve patients (6 males, aged 54-78 years, median 65 years), with carcinoid diarrhea and 19 healthy subjects (7 males, aged 50-78 years, median 61 years) were included. Rectal mechanical and heat stimulation was used for assessment of rectal mechano-sensory properties. RESULTS: Overall, 5.3% higher temperatures were needed to elicit sensory responses in patients with carcinoid diarrhea than in healthy subjects (P = 0.015). Posthoc analyses revealed that the sensory threshold to heat was 48.1 ± 3.1℃ in patients vs 44.7 ± 4.7℃ in healthy subjects (P = 0.041). In contrast, patients and healthy subjects showed no overall differences in rectal sensory response to mechanical distension (P = 0.731) or rectal compliance (P = 0.990). CONCLUSIONS: Patients with carcinoid diarrhea have higher sensory thresholds to heat stimulation in comparison to healthy subjects, but normal rectal sensation to mechanical distension and normal compliance. Therefore, treatment of carcinoid diarrhea should aim at prolonging gastrointestinal transit and decreasing secretion, rather than modifying rectal mechano-sensory function.
Amines ; Carcinoid Tumor* ; Compliance ; Diarrhea* ; Flushing ; Gastrointestinal Transit ; Hot Temperature ; Humans ; Hypersensitivity ; Male ; Neuroendocrine Tumors ; Rectum ; Sensation ; Sensory Thresholds ; Serotonin

BACKGROUND/AIMS: The paucity of knowledge regarding gastrointestinal motility in patients with neuroendocrine tumors and carcinoid diarrhea restricts targeted treatment. 3D-Transit is a novel, minimally invasive, ambulatory method for description of gastrointestinal motility. The system has not yet been evaluated in any group of patients. We aimed to test the performance of 3D-Transit in patients with carcinoid diarrhea and to compare the patients' regional gastrointestinal transit times (GITT) and colonic motility patterns with those of healthy subjects. METHODS: Fifteen healthy volunteers and seven patients with neuroendocrine tumor and at least 3 bowel movements per day were investigated with 3D-Transit and standard radiopaque markers. RESULTS: Total GITT assessed with 3D-Transit and radiopaque markers were well correlated (Spearman's rho = 0.64, P = 0.002). Median total GITT was 12.5 (range: 8.5-47.2) hours in patients versus 25.1 (range: 13.1-142.3) hours in healthy (P = 0.007). There was no difference in gastric emptying (P = 0.778). Median small intestinal transit time was 3.8 (range: 1.4-5.5) hours in patients versus 4.4 (range: 1.8-7.2) hours in healthy subjects (P = 0.044). Median colorectal transit time was 5.2 (range: 2.9-40.1) hours in patients versus 18.1 (range: 5.0-134.0) hours in healthy subjects (P = 0.012). Median frequency of pansegmental colonic movements was 0.45 (range: 0.03-1.02) per hour in patients and 0.07 (range: 0-0.61) per hour in healthy subjects (P = 0.045). CONCLUSIONS: Three-dimensional Transit allows assessment of regional GITT in patients with diarrhea. Patients with carcinoid diarrhea have faster than normal gastrointestinal transit due to faster small intestinal and colorectal transit times. The latter is caused by an increased frequency of pansegmental colonic movements.
Capsules ; Carcinoid Tumor* ; Colon ; Diarrhea* ; Gastric Emptying ; Gastrointestinal Motility ; Gastrointestinal Transit* ; Healthy Volunteers ; Humans ; Neuroendocrine Tumors