title: Reliability of symptom analysis during carbohydrate hydrogen-breath tests.
abstract: OBJECTIVE
  Relevance of symptom analysis during hydrogen breath test (HBT) for establishing a clinical diagnosis of sugar intolerance is reviewed.
  
  
  RESULTS
  Evaluation of symptoms developed in response to the ingestion of 50 g lactose could represent a simple screening test to select patients for lactose intolerance testing. Patients who do not develop symptoms do not need to be referred for HBT. In addition, symptoms reported by patients during a negative HBT cannot be at all times attributed to a false-negative test; instead, a 'nocebo' effect is likely to be implicated. On the other hand, in a double-blind randomized study, a dose of 25 g fructose was suggested as the most appropriate for testing individuals with suspected fructose malabsorption, whereas symptom reliability to diagnose fructose intolerance was inaccurate.
  
  
  CONCLUSIONS
  Whereas the development of symptoms after a positive HBT may indicate sugar intolerance, it is still not clear whether the absence of symptoms after sugar malabsorption gives any indication as to the role of that sugar in the genesis of patient's complaints. Further studies should evaluate whether the disappearance of symptoms with a sugar-restricted diet after a positive HBT is a better diagnostic criterion of sugar intolerance than the development of symptoms.
authors.affiliation: Department of Gastroenterology, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Hospital Universitary Mutua Terrassa, University of Barcelona, Terrassa, Barcelona, Spain. ffbanares@mutuaterrassa.es
authors.forename: Fernando
authors.initials: F
authors.lastname: Fernández-Bañares
mesh_terms: D001944:Breath Tests / Q000379:methods*; D004032:Diet; D019422:Dietary Sucrose / Q000009:adverse effects* / Q000378:metabolism; D005632:Fructose / Q000009:adverse effects* / Q000378:metabolism; D006801:Humans; D006859:Hydrogen / Q000378:metabolism*; D007410:Intestinal Diseases / Q000209:etiology* / Q000378:metabolism; D007785:Lactose / Q000009:adverse effects* / Q000378:metabolism; D007787:Lactose Intolerance / Q000150:complications / Q000175:diagnosis; D008286:Malabsorption Syndromes / Q000150:complications / Q000175:diagnosis* / Q000378:metabolism; D015203:Reproducibility of Results
chemical_list: D019422:Dietary Sucrose; D005632:Fructose; D006859:Hydrogen; D007785:Lactose