Gastroenterology

Gastroenterology

Volume 145, Issue 4, October 2013, Pages 749-757
Gastroenterology

Original Research
Full Report: Clinical—Alimentary Tract
Rome III Functional Constipation and Irritable Bowel Syndrome With Constipation Are Similar Disorders Within a Spectrum of Sensitization, Regulated by Serotonin

https://doi.org/10.1053/j.gastro.2013.07.014Get rights and content

Background & Aims

Patients with irritable bowel syndrome with constipation (IBS-C) and patients with functional constipation (FC) have similar symptoms, and these disorders overlap in their diagnostic features. Little is known about their overlap in physiology or the involvement of serotonin signaling. We investigated relationships between platelet-depleted plasma concentrations of serotonin, gastrointestinal symptoms, and motor−sensory function in patients with FC or IBS-C compared with healthy volunteers (controls).

Methods

We measured platelet-depleted plasma concentrations of serotonin in fasting and fed individuals with IBS-C (n = 23; 19−50 years old), FC (n = 11; 25−46 years old), and controls (n = 23; 20−49 years old) recruited in Manchester, UK. We also quantified abdominal and bowel-related symptoms, rectal sensitivity, oro-cecal transit, and colonic (whole intestine) transit.

Results

Patients with IBS-C or FC had similar baseline symptoms, bowel habits, oro-cecal and colonic transit, and fasting concentrations of serotonin and response to meal ingestion. Only patients with IBS-C had increased symptoms after ingestion of a meal (P < .001)—these patients tended to have lower sensory thresholds than patients with FC. Defecation frequency in the combined group of patients with IBS-C or FC correlated inversely with serotonin concentration (r = −0.4; P = .03). Serotonin concentration also correlated with pain threshold (r = 0.4; P = .02) and stool threshold (r = 0.5; P = .06), which correlated inversely with defecation frequency (r = −0.3; P = .10).

Conclusions

FC and IBS-C, based on Rome III criteria, are not distinct disorders, symptomatically or physiologically. Instead, they appear to lie in a spectrum of visceral sensitivity modulated by serotonin signaling. Symptom response to meal ingestion should be considered in patient classification.

Section snippets

Subjects

This study was carried out on 24 female IBS-C patients (aged 19−50 years), 12 female FC patients (aged 25−46 years), and 24 female HVs (aged 20−49 years). Patients were recruited from the Outpatients Department of the University Hospitals of South Manchester (tertiary patients excluded), local general practices, advertisement in regional newspapers, and an existing departmental volunteer pool of patients, and all satisfied the Rome III criteria for either IBS-C or FC.1 No subjects had

Results

Table 1 shows the demographic and 7-day diary data for FC and IBS-C patients, and HVs. One IBS-C patient and one HV did not complete the study for personal reasons and one FC patient emigrated. Both FC and IBS-C patients reported more abdominal symptoms and bowel movement−associated symptoms than HVs (P < .001), with IBS-C patients reporting more abdominal pain and bloating than FC patients (P < .04). In addition, 45% (5 of 11) of FC patients and 69% (16 of 23) of IBS-C patients reported

Discussion

This is the first study to show that increased PDP 5-HT concentration associates with reduced visceral sensitivity and stool frequency in patients with constipation. Our data confirm that there is much symptom and physiological overlap between patients with IBS-C and FC, both in terms of abdominal and bowel movement−associated symptoms, and gastrointestinal transit, with the only difference being that IBS-C patients have an increase in abdominal symptoms with meal ingestion and tend to reside

Acknowledgments

We would like to thank Professor Shaheen Hamdy for acting as on-site day-to-day supervisor to Dr Shekhar, following Professor Houghton's relocation to the Mayo Clinic.

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    This article has an accompanying continuing medical education activity on page e13. Learning Objective: Upon completion of these questions, successful learners will be able to discuss the symptoms and pathophysiology of irritable bowel syndrome with constipation and functional constipation.

    Conflicts of interest The authors disclose no conflicts.

    Funding Supported by custodial research funds held by University Hospital of South Manchester NHS Foundation Trust.

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