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Table 3 Assessment of normal gut functiona

From: 'Gut health': a new objective in medicine?

Assessments and parameters Descriptions
Subjective assessments of well-being
Validated questionnaires useful to assess quality of life and gut health IBS-Quality of Life (IBS-QOL) Validated for assessment of quality of life specific to IBS: 34 questions
  Inflammatory Bowel Disease Questionnaire (IBDQ) Validated for assessment of health-related quality of life (HRQoL) in adult patients with IBD
  Bowel Disease Questionnaire (BDQ) Validated to distinguish patients with functional and organic GI disease
  Health Status Questionnaire (HSQ-12) Validated for assessment of HRQoL in the general population
  Short Form Health Survey SF-12 (SF-12) Validated for assessment of HRQoL in the general population
GI symptom scores IBS Severity Scoring System (IBS-SSS) Validated for scoring lower GI symptoms on the basis of nine questions; range of 0 to 500 points
  Short Form Leeds Dyspepsia Questionnaire (SF-LDQ) Validated instrument for measuring the presence and severity of dyspepsia
  Gastrointestinal Symptom (GIS) profile Validated for assessment of symptoms of functional dyspepsia; 10 questions
  Subject's Global Assessment of Relief (SGA) Validated assessment of the impact of treatment on IBS-related symptoms; 1 question
  IBS Global Assessment of Improvement (IBS-GAI) ("adequate relief") Asks participants if, compared to the way they felt before entering the study, their IBS symptoms have changed over the past 7 days; 1 question
  Functional Bowel Disorder Severity Index (FBDSI) Validated score for assessment of patient perception of abdominal pain in IBS
  Numeric Rating Scale (NRS) for assessment of pain Validated in IBS patients
  Visceral Sensitivity Index (VSI) Validated psychometric instrument that measures GI symptom-specific anxiety
  Bristol Stool Scale/Bristol Stool Chart A medical aid designed to classify the form of human faeces into seven categories
  Gastrointestinal Symptom Rating Scale  
Eating habits Food frequency questionnaire 7-day diet history assessed using computer software
Objective parameters
Markers of functionality Gastric function pH metry in the esophagus [6, 7] and stomach [13], gastroesophageal reflux episodes (< 50/day, <60 minutes total), viscosity of the luminal content using a viscometer, stool weight (> 100 g/d, <500 g/d) and stool consistency (water content)
  Permeability measurements Tracer molecules (lactulose/mannitol, 51Cr-EDTA, PEG);
  Motility tests Barostat, gastric scintigraphy, 13C urea breath test (gastric emptying) and lactulose hydrogen breath test (normal range: 40 to 240 hours)
  Transit time Radiopaque pellets (Hinton test) and isotope-labelled test meal (normal range: 24 to 168 hours)
  Digestion parameters Stool elastase (> 200/g) and stool fat (< 7 g/d), carbohydrate breath tests, anthropometry and micronutrient analysis
Markers of intestinal integrity Epithelial integrity Histology (villus height/crypt depth ratio, mitosis and apoptosis), mucus secretion (mucins and trefoil peptides) and Ussing chamber (ion fluxes and electric potentials)
  Specific molecules E-cadherin, growth factors, tight junction molecules, α1-antitrypsin in faeces and LPS in blood
  Antimicrobial peptides α- and β-defensins, calprotectin, lysozyme or neutrophil-derived elastase in faeces
Marker of intact immunity Cell counts and phenotyping Differential blood count and FACS analysis, histopathology of intestinal biopsies and immunohistochemistry of intestinal biopsies
  Cell mediators and cytokines Inflammatory cytokines (IL-1, IL-6 and TNFα), anti-inflammatory cytokines (IL-10 and TGFβ), regulatory cytokines (IL-2, sIL-2R, IL-4, IL-5 and so on), proteases (tryptase, chymases, chymotrypsin and so on), immunoglobulins (IgA, sIgA and IgE) and others (retinoic acid, neuropeptides and so on)
  Functional assays Cell cultures and cocultures, DTH response, phagocytosis, chemotaxis, oxidative burst (superoxide anion generation) and NK cell activity
Analysis of the intestinal microbiome Classical approaches Bacterial culture and toxin measurements
  New approaches Metagenomics (PCR and full bacterial sequencing), metabonomics (metabolic capacity of the microbiome)
  1. aIBS, irritable bowel syndrome; IBD, inflammatory bowel disease; GI, gastrointestinal; 51CR-EDTA, chromium ethylenediaminetetraacetic acid; PEG, polyethylene glycol; LPS, lipopolysaccharide; FACS, fluorescence-activated cell sorting; IL, interleukin; TNF, tumour necrosis factor; TGF, transforming growth factor; sIL-2R, soluble interleukin 2 receptor; Ig, immunoglobulin; sIgA, secretory immunoglobulin A; DTH, delayed-type hypersensitivity; NK, natural killer; PCR, polymerase chain reaction.