Irritable bowel syndrome: a comparison of subtypes

Tannin-based supplementation influences gut microbiota composition and activity in IBS-D patients with a potential impact on symptoms: a pilot study

As the involvement of the intestinal microbiota in the etiopathology of irritable bowel syndrome, subtype diarrhoea (IBS-D) is now increasingly recognised, a preliminary, quasi-experimental, before-after and prospective study was conducted on 28 patients to test the effect of a tannin-based supplement on the composition and activity of the microbiota, after 8 weeks of treatment. No statistically significant differences were found in α- or β-diversity. However, sparse Partial Least Squares Discriminant Analysis (sPLS-DA) and Boruta algorithm did reveal significant changes in the relative abundance of specific groups of bacteria, highlighting the involvement of recognized of IBS-D biomarkes, namely Blautia (adj p = 3.5 × 10-11), Eubacterium hallii group (adj p = 5.1 × 10-12) and Dorea (adj p = 1.8 × 10-18), which resulted significantly depleted by the treatment. The modulation of the composition of the gut microbiota had an impact also in the production of short chain fatty acids (SCFAs), which were modulated: acetate and butyrate (n.s. and p = 0.000143) increased while propionate and formate resulted to be significantly reduced (p = 0.00476 and p = 0.00011, respectively), following the supplementation. Finally, the sPLS analysis showed that the strongest association between faecal microbiome composition and clinical symptoms of IBS-D was given by Catenibacterium, which showed a positive correlation with evacuation-related symptoms. Such preliminary findings suggest that tannin supplementation could play an outstanding role in microbiota modulation in IBS-D patients, potentially improving their symptomatology, by selectively acting on the growth and the activity of specific groups of taxa.

Utility of irritable bowel syndrome subtypes and most troublesome symptom in predicting disease impact and burden

BACKGROUND

Little is known about the characteristics of individuals with irritable bowel syndrome (IBS) according to stool subtype or the most troublesome symptom reported by the individual, or whether these are useful in predicting the impact of IBS.

METHODS

We collected demographic, gastrointestinal, and psychological symptoms, healthcare usage and direct healthcare costs, impact on work and activities of daily living, and quality of life data from individuals with Rome IV-defined IBS.

KEY RESULTS

We recruited 752 people with Rome IV IBS. Individuals with IBS-D reported a poorer disease-specific quality of life than those with IBS-C or IBS-M (mean (SD) IBS-QOL 45.3 (23.0) for IBS-D, vs. 52.3 (19.9) for IBS-C, vs. 49.4 (22.0) for IBS-M, p = 0.005). Mean (SD) IBS-QOL scores were also lower amongst those who reported diarrhea (44.8 (22.3)) or urgency (44.6 (22.3)) as their most troublesome symptom, compared with those reporting abdominal pain (52.2 (22.9)), constipation (49.5 (21.8)), or abdominal bloating or distension (50.4 (21.3)). However, there were no differences in mean EQ-5D scores, IBS severity, levels of anxiety, depression, somatoform symptom-reporting, or gastrointestinal symptom-specific anxiety. Direct healthcare costs of IBS were similar across all subtypes and all most troublesome symptom groups, although some differences in work productivity and social leisure activities were detected.

CONCLUSIONS AND INFERENCES

There appears to be limited variation in the characteristics of individuals with Rome IV IBS based on both stool subtypes and most troublesome symptom reported, suggesting that gastrointestinal symptoms alone have limited ability to predict disease impact and burden.

Identification of putative transcriptomic biomarkers in irritable bowel syndrome (IBS): Differential gene expression and regulation of TPH1 and SERT by vitamin D

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders and affects approximately 4% of the global population. The diagnosis of IBS can be made based on symptoms using the validated Rome criteria and ruling out commonly occurring organic diseases. Although biomarkers exist for "IBS mimickers" such as celiac disease and inflammatory bowel disease (IBD), no such test exists for IBS. DNA microarrays of colonic tissue have been used to identify disease-associated variants in other gastrointestinal (GI) disorders. In this study, our objective was to identify biomarkers and unique gene expression patterns that may define the pathological state of IBS. Mucosal tissue samples were collected from the sigmoid colon of 29 participants (11 IBS and 18 healthy controls). DNA microarray analysis was used to assess gene expression profiling. Extraction and purification of RNA were then performed and used to synthesize cDNA. Reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) was employed to identify differentially expressed genes in patients diagnosed with IBS compared to healthy, non-IBS patient-derived cDNA. Additional testing probed vitamin D-mediated regulation of select genes associated with serotonergic metabolism. DNA microarray analyses led to the identification of 858 differentially expressed genes that may characterize the IBS pathological state. After screening a series of genes using a combination of gene ontological analysis and RT-qPCR, this spectrum of potential IBS biomarkers was narrowed to 23 genes, some of which are regulated by vitamin D. Seven putative IBS biomarkers, including genes involved in serotonin metabolism, were identified. This work further supports the hypothesis that IBS pathophysiology is evident within the human transcriptome and that vitamin D modulates differential expression of genes in IBS patients. This suggests that IBS pathophysiology may also involve vitamin D deficiency and/or an irregularity in serotonin metabolism.

Extraintestinal manifestations in irritable bowel syndrome: A systematic review

BACKGROUND

Irritable bowel syndrome (IBS) is characterized by abdominal pain and altered bowel habits. Further, IBS patients experience a high degree of extraintestinal symptoms.

OBJECTIVES

The aim of this review was to describe the relation between IBS and extraintestinal manifestations and mechanisms and treatments of these extraintestinal manifestations.

DESIGN

The study was performed as a systematic review.

DATA SOURCES AND METHODS

Search terms including extraintestinal manifestations or somatization and IBS were used to scrutinize for publications in Pubmed. In total, 630 publications were identified and 80 were finally included in this review.

RESULTS

About 50% of all IBS patients have extraintestinal manifestations in addition to gastrointestinal symptoms. Somatic pain, fatigue, and sleeping disturbances are most common, and most often described in women. Both extraintestinal manifestations and psychological distress are associated with exaggerated gastrointestinal symptoms, impaired quality of life, and difficulties to treat IBS symptoms. The extraintestinal manifestations render an excess of healthcare costs. Varying etiology and pathophysiology to IBS are discussed, and many patients express a general hypersensitivity. Extraintestinal symptoms are seldom documented at clinical healthcare or included in the assessment of treatment outcomes. A good patient-physician relationship and strengthening of coping mechanisms have rendered less gastrointestinal symptoms, psychological distress, and somatization. Altered lifestyle habits may improve both gastrointestinal and extraintestinal symptoms. Pharmacological treatment, including antidepressant drugs, should be considered when lifestyle advice fails. Teamwork between different specialists and healthcare providers may be of importance in the wide range of symptoms and extraintestinal manifestations.

CONCLUSION

Extraintestinal manifestations are common in IBS patients and is associated with worse suffering and difficulties to treat symptoms. Evaluation and treatment of IBS patients should consider also extraintestinal manifestations and their treatment outcome. Establishment of good relationship, strengthening of coping mechanisms, and education in healthier lifestyle habits are crucial in the management of these patients.

Systematic review, meta-analysis with subgroup analysis of hypnotherapy for irritable bowel syndrome, effect of intervention characteristics

BACKGROUND

Hypnotherapy has been shown to be effective at relieving global gastrointestinal symptoms (GGS) in irritable bowel syndrome (IBS). This study examines the impact of hypnotherapy delivery and participant characteristics on IBS outcomes.

METHODS

This systematic review searched CINAHL, Cochrane Library, Conference Citation Index, Embase, PubMed, PsycARTICLES, PsychINFO, Science Citation index-expanded, Social Science Citation Index. Titles and abstracts, then full-text articles were screened against inclusion criteria: trials with a concurrent comparator of hypnotherapy in adults with IBS diagnosed using Manning or ROME criteria, which provided symptom data. Included studies were extracted and assessed for bias using Cochrane Collaboration 2011 guidance. Random-effects meta-analysis was conducted with sub-group analysis to assess the impact of delivery characteristics on outcomes.

RESULTS

Twelve trials were included, 7 in the meta-analyses. Hypnotherapy reduced the risk of GGS, but this was not statistically significant, (standardised mean difference (SMD) 0.24, [-0.06, 0.54], I² 66 %). Higher frequency of sessions (≥1/week) reduced GGS (SMD 0.45 [0.23,0.67] I² 0 %), as did higher volumes of intervention (≥8 sessions with ≥6 h of contact) (SMD 0.51 [0.27,0.76] I² 0 %) and group interventions (SMD 0.45 [0.03, 0.88] I² 62 %). Only volume of intervention produced a significant effect between the subgroups.

CONCLUSION

This review suggests that high volume hypnotherapy is more beneficial than low and should be adopted for GDH. Both high frequency and group interventions are effective in reducing GGS in IBS. However, the sample size is small and more studies are needed to confirm this.

Serum Levels of Chemerin, Apelin, and Adiponectin in Relation to Clinical Symptoms, Quality of Life, and Psychological Factors in Irritable Bowel Syndrome

BACKGROUND

Adipokines have endocrine roles in metabolism and immunity. Dysregulation of adipokine levels is associated with several diseases with chronic inflammation. We aimed to assess the serum concentrations of chemerin, apelin, and adiponectin in irritable bowel syndrome (IBS). Furthermore, we evaluated the possible association of these adipokines with clinical symptoms, quality of life (QoL), and psychological factors.

MATERIALS AND METHODS

In this case-control study, 114 male and female IBS patients were recruited from outpatient clinics. Along with the IBS patients, 114 sex and age-matched healthy volunteers were recruited. Patients filled in the questionnaires of the IBS severity scoring system (IBSSS), gastrointestinal (GI) and somatic symptoms, IBS specific QoL (IBS-QoL), and psychological disorders, and went to the lab for blood sampling.

RESULTS

Serum levels of both adiponectin and apelin were significantly (P=0.04, 0.03, respectively) lower, whereas chemerin was significantly (P=0.01) higher in IBS patients. Chemerin was higher in IBS-D compared with both IBS-C and IBS-A, while apelin and adiponectin were not different between subtypes. After adjustments for confounders only, chemerin had a positive association with IB severity scoring system and GI symptoms. Furthermore, chemerin had positive associations, whereas apelin and adiponectin had inverse associations with somatic symptoms and psychological factors. There were no significant associations between adipokines including chemerin, apelin, and adiponectin, and IBS-QoL.

CONCLUSIONS

Chemerin had significant associations with both the severity of clinical symptoms and psychological factors in IBS; thus, it could be considered as a potential therapeutic target in these patients; however, further studies are needed.

Cognitive and Behavioral Differences Between Subtypes in Refractory Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a functional gastrointestinal syndrome consisting of different bowel pattern subtypes: diarrhea predominant (IBS-D), constipation predominant (IBS-C), and alternating (IBS-A). This paper aimed to identify whether (a) psychological factors implicated in the cognitive behavioral model of IBS were differentially associated with bowel pattern subtypes, (b) whether there were differences in symptom severity and work and social adjustment across the IBS-subtypes. Analysis was conducted on baseline data of 557 individuals with refractory IBS recruited into the Assessing Cognitive Therapy in Irritable Bowel (ACTIB) randomized controlled trial. Correlations assessed the associations between psychological factors, stool patterns, symptom severity, and work and social adjustment. Hierarchical regressions identified whether cognitive and behavioral factors were significantly associated with frequency of loose/watery stools, hard/lumpy stools and symptom severity while controlling for affective (anxiety and depression) and demographic factors (age, gender, symptom duration). One-way ANOVAs were conducted to assess differences across Rome III classified subtypes (IBS-A, D and C) in cognitive, behavioral, affective, symptom severity, and adjustment measures. Psychological factors were significantly associated with symptom severity and work and social adjustment. Increased avoidance behavior and unhelpful gastrointestinal (GI) cognitions were significantly associated with higher frequency of loose/watery stools. Increased control behaviors were associated with higher frequency of hard/lumpy stools. Cognitive and behavioral differences were significant across the Rome III classified IBS subtypes. There were no differences in anxiety, depression, overall symptom severity, or work and social adjustment. The results are discussed in terms of their utility in tailoring cognitive behavioral treatments to IBS subtypes.

Symptom Comparisons Between Asian American and White American Women With Irritable Bowel Syndrome

There is little information on racial/ethnic characteristics of patients with irritable bowel syndrome. In this study, we determined whether the severity of symptoms (gastrointestinal, psychological distress), cognitive beliefs about irritable bowel syndrome, and life impacts (life interference, health-related quality of life) differ between Asian American and White American women with irritable bowel syndrome. We also look at the relationships among these variables. Asian American women (N = 21) and age- and design-matched White American women (N = 63) with irritable bowel syndrome were included. Data were collected from questionnaires and a 28-day daily diary (e.g., abdominal pain, depression). The percent of days with moderate/severe abdominal pain and psychological distress were significantly higher, and constipation- and diarrhea-dominant bowel pattern subtypes were prevalent in White Americans as compared with Asian Americans. Positive relationships of gastrointestinal symptoms with psychological distress, and of gastrointestinal and psychological symptoms with negative cognitive beliefs and negative life impact, were observed in White Americans. Further studies to evaluate contributing (e.g., cultural-environmental, pathophysiological, diet) factors of symptom characteristics in Asian Americans are suggested. Our study provides useful information for healthcare providers to understand symptoms and cultural factors and the potential for culturally tailored symptom management for this patient group.

Endocrine regulation of gut function - a role for glucagon-like peptide-1 in the pathophysiology of irritable bowel syndrome

NEW FINDINGS

What is the topic of this review? Pathophysiological changes linked to irritable bowel syndrome (IBS) include stress and immune activation, changes in gastrointestinal microbial and bile acid profiles and sensitization of extrinsic and intrinsic gut neurons. This review explores the potential role for L-cells in these pathophysiological changes. What advances does it highlight? L-cells, which secrete glucagon-like peptide-1 in response to nutrients, microbial factors, bile acids and short-chain fatty acids, may sense IBS-related changes in the luminal environment. Glucagon-like peptide-1 can act as a hormone, a paracrine factor or a neuromodulatory factor and, through its actions on central or peripheral neurons, may play a role in gastrointestinal dysfunction.

ABSTRACT

The prevalent and debilitating functional bowel disorder, irritable bowel syndrome (IBS), is characterized by symptoms that include abdominal pain, bloating, diarrhoea and/or constipation. The heterogeneity of IBS underscores a complex multifactorial pathophysiology, which is not completely understood but involves dysfunction of the bi-directional signalling axis between the brain and the gut. This axis incorporates efferent and afferent branches of the autonomic nervous system, circulating endocrine hormones and immune factors, local paracrine and neurocrine factors and microbial metabolites. L-cells, which are electrically excitable biosensors embedded in the gastrointestinal epithelium, secrete glucagon-like peptide-1 (GLP-1) in response to nutrients in the small intestine. However, they appear to function in a different manner more distally in the gastrointestinal tract, where they are activated by luminal factors including short-chain fatty acids, bile acids and microbial metabolic products, all of which are altered in IBS patients. Glucagon-like peptide-1 can also interact with the hypothalamic-pituitary-adrenal stress axis and the immune system, both of which are activated in IBS. Given that a GLP-1 mimetic has been found to alleviate acute pain symptoms in IBS patients, GLP-1 might be important in the manifestation of IBS symptoms. This review assesses the current knowledge about the role of GLP-1 in IBS pathophysiology and its potential role as a signal transducer in the microbiome-gut-brain signalling axis.

Comparison and Assessment of Flixweed and Fig Effects on Irritable Bowel Syndrome with Predominant Constipation: A Single-Blind Randomized Clinical Trial

BACKGROUND

Irritable bowel syndrome with predominant constipation (IBS-C) is a common digestive disorder. The current therapy is inadequate and evidence regarding the effect of herbal therapies on the relief of affected individuals is insufficient. The aim of this study was to investigate the beneficial effects of flixweed and fig consumption on IBS-C symptoms.

METHODS

150 patients with IBS-C were enrolled in this randomized, controlled trial. All patients were randomly assigned to three groups and received an intervention for four months. The IBS severity score system and quality-of-life questionnaires were used for evaluating IBS-C symptoms. C-reactive protein levels, frequency of defecation and hard stool were also assessed.

RESULTS

Consumption of flixweed or fig, compared to a control group, caused a significant improvement in IBS symptoms including frequency of pain, distention, frequency of defecation and hard stool. Also, the findings showed a significant increase in quality of life, as well as satisfaction with overall bowel habits. However, flixweed and fig intake had no significant effects on abdominal pain severity and C-reactive protein levels.

CONCLUSIONS

In conclusion, consumption of flixweed or fig for four months would be a useful therapy for alleviating IBS-C symptoms and can be a beneficial option for first-line treatment.

肝郁脾虚型肠易激综合征患者应用中医护理效果分析

目的

观察肝郁脾虚型肠易激综合征(irritable bowel syndrome, IBS)应用中医护理效果分析.

方法

将90例肝郁脾虚型IBS患者随机分为对照组和观察组, 各45例. 对照组给予常规护理, 如心理护理、生活护理、饮食护理、健康宣教、运动干预等. 观察组在对照组基础上应用中医护理, 均护理2 wk, 观察生活质量评分, 心理状态评分和临床症状变化情况.

结果

2组生理功能、生理职能、躯体疼痛、总体健康、生命活力、社会功能、情感职能、精神健康等评分组内比较, 差异有统计学意义(P<0.05), 且护理后观察组评分明显高于对照组(P<0.05). 与护理前比较, 2组护理1、2 wk时焦虑自评量表(Self-rating Anxiety Scale, SAS)和抑郁自评量表(Self-rating Depression Scale, SDS)评分, 差异均有统计学意义(P<0.05); 且与对照组同期比较, 观察组SAS和SDS评分降低, 差异有统计学意义(P<0.05). 2组护理后腹痛、腹胀、大便次数、黏液便、大便性状等积分均低于治疗前(P<0.05); 且护理后观察组症状积分明显低于对照组(P<0.01).

结论

肝郁脾虚型IBS患者应用中医护理后能明显减轻患者焦虑、抑郁评分, 提高患者生活质量和改善临床症状.

Irritable bowel syndrome subtypes: Clinical and psychological features, body mass index and comorbidities

BACKGROUND

Irritable bowel syndrome (IBS) is classified into subtypes according to bowel habit.

OBJECTIVE

To investigate whether there are differences in clinical features, comorbidities, anxiety, depression and body mass index (BMI) among IBS subtypes.

METHODS

The study group included 113 consecutive patients (mean age: 48 ± 11 years; females: 94) with the diagnosis of IBS. All of them answered a structured questionnaire for demographic and clinical data and underwent upper endoscopy. Anxiety and depression were assessed by the Hospital Anxiety and Depression scale (HAD).

RESULTS

The distribution of subtypes was: IBS-diarrhea (IBS-D), 46%; IBS-constipation (IBS-C), 32%, and mixed IBS (IBS-M), 22%. IBS overlap with gastroesophageal reflux disease (GERD), functional dyspepsia, chronic headache and fibromyalgia occurred in 65.5%, 48.7%, 40.7% and 22.1% of patients, respectively. Anxiety and/or depression were found in 81.5%. Comparisons among subgroups showed that bloating was significantly associated with IBS-M compared to IBS-D (odds ratio-OR-5.6). Straining was more likely to be reported by IBS-M (OR 15.3) and IBS-C (OR 12.0) compared to IBS-D patients, while urgency was associated with both IBS-M (OR 19.7) and IBS-D (OR 14.2) compared to IBS-C. In addition, IBS-M patients were more likely to present GERD than IBS-D (OR 6.7) and higher scores for anxiety than IBS-C patients (OR 1.2). BMI values did not differ between IBS-D and IBS-C.

CONCLUSION

IBS-M is characterized by symptoms frequently reported by both IBS-C (straining) and IBS-D (urgency), higher levels of anxiety, and high prevalence of comorbidities. These features should be considered in the clinical management of this subgroup.

Effect of vitamin D on gastrointestinal symptoms and health-related quality of life in irritable bowel syndrome patients: a randomized double-blind clinical trial

BACKGROUND

Low-grade mucosal inflammation and immune activation are involved in the pathogenesis of irritable bowel syndrome (IBS). Furthermore, IBS symptoms are associated with a significantly higher prevalence of psychological distress, which in itself results into an impaired quality of life (QoL). Vitamin D could ameliorate the symptoms of patients suffering from IBS through its beneficial effects on psychological factors and inflammation.

METHODS

A total of 90 IBS patients participated in this double-blind, randomized, placebo-controlled study. Participants were randomly selected to receive either 50 000 IU vitamin D3 or a placebo fortnightly for a period of 6 months. Patients reported their IBS symptoms at the baseline and monthly during intervention periods. The IBS severity score system (IBSSS) and IBS-specific QoL questionnaires were used at the baseline and postintervention.

KEY RESULTS

Over the 6-month intervention period, a significantly greater improvement in IBS symptoms such as abdominal pain and distention, flatulence, rumbling, and overall gastrointestinal (GI) symptoms (except dissatisfaction with bowel habits) was observed in the patients receiving vitamin D as compared to the placebo group. The IBSSS and the IBS-QoL scores in the vitamin D group significantly improved compared to the placebo group postintervention (mean IBSSS score change: -53.82 ± 23.3 vs -16.85 ± 25.01, p < 0.001, respectively; mean IBS-QoL score change: 14.26 ± 3 vs 11 ± 2.34, p < 0.001, respectively).

CONCLUSIONS & INFERENCES

Vitamin D seems to be an effective and safe option to improve QoL and symptoms of IBS. ClinicalTrials.gov (NCT02579902).

New and emerging therapies for the treatment of irritable bowel syndrome: an update for gastroenterologists

Irritable bowel syndrome is a functional bowel disorder with gastrointestinal symptoms (e.g. abdominal pain, straining, urgency, incomplete evacuation, nausea, and bloating) that occur alongside bowel function alterations (i.e. constipation, diarrhea, or both). Patients with irritable bowel syndrome may also experience comorbid anxiety and depression. Irritable bowel syndrome is common, with a prevalence estimated between 3% and 28%, affecting patient health and quality of life. Patients with moderate or severe irritable bowel syndrome generally seek medical care, whereas those with milder symptoms may choose self-management. Most patients with irritable bowel syndrome receive outpatient care, but irritable bowel syndrome-related hospitalizations do occur. The pathophysiology of irritable bowel syndrome is multifactorial (i.e. genetics, immune components, changes in the gut microbiota, disturbances in physiologic stress response systems, and psychosocial factors). Management of irritable bowel syndrome can include lifestyle changes, dietary interventions, counseling, psychologic medication, and agents that affect gastrointestinal motility. A number of therapies have emerged in recent years with clinical trial data demonstrating efficacy and safety for patients with irritable bowel syndrome, including agents that target gastrointestinal motility (i.e. linaclotide), gastrointestinal opioid receptors (i.e. asimadoline, eluxadoline), and gut microbiota (i.e. rifaximin). Linaclotide has been shown to significantly improve stool frequency and abdominal pain compared with placebo in constipation-predominant irritable bowel syndrome (number needed to treat, 5.1). Asimadoline shows efficacy in patients with moderate-to-severe irritable bowel syndrome-related pain. Rifaximin provided adequate relief of global irritable bowel syndrome symptoms versus placebo for a significantly greater percentage of patients with diarrhea-predominant irritable bowel syndrome (p < 0.001). Management that encompasses all aspects of irritable bowel syndrome (gastrointestinal symptoms) and comorbid psychologic symptoms (e.g. anxiety or depression) is important for improving overall patient health and well-being.

Alterations in serotonin metabolism in the irritable bowel syndrome

BACKGROUND

Alterations in serotonin (5-HT) metabolism have been postulated to play a role in the pathogenesis of irritable bowel syndrome (IBS). However, previous reports regarding 5-HT metabolism in IBS are contradicting.

AIM

To compare platelet poor plasma (PPP) 5-HT and 5-hydroxyindole acetic acid (5-HIAA) levels and their ratio in a large cohort of IBS patients and healthy controls (HC), including IBS-subgroup analysis.

METHODS

Irritable bowel syndrome patients and HC were evaluated for fasting PPP 5-HT and 5-HIAA levels. Furthermore, GI-symptom diary, GSRS, quality of life, anxiety and depression scores were assessed in the 2 weeks before blood sampling.

RESULTS

One hundred and fifty four IBS patients and 137 HC were included. No differences were detected in plasma 5-HT between groups. The 5-HIAA concentrations and 5-HIAA/5-HT ratio were significantly lower in IBS compared to HC: 24.6 ± 21.9 vs. 39.0 ± 29.5 μg/L (P < 0.001) and 8.4 ± 12.2 vs. 13.5 ± 16.6 (P < 0.01), respectively. Subtype analysis for 5-HIAA showed all IBS subtypes to be significantly different from HC. The 5-HIAA/5-HT ratio was significantly lower in the IBS-M subtype vs. HC. Linear regression analysis points to an influence of gender but not of GI-symptoms, psychological scores or medication use.

CONCLUSIONS

We demonstrated that fasting 5-HT plasma levels are not significantly different in IBS patients compared to controls. However, decreased 5-HIAA levels and 5-HIAA/5-HT ratio in IBS patients may reflect altered serotonin metabolism in IBS. Gender affects 5-HIAA levels in IBS patients, but no effects of drugs, such as SSRIs, or higher GI-symptom or psychological scores were found.