title: Small intestinal bacterial overgrowth as an uncommon cause of false positive lactose hydrogen breath test among patients with diarrhea-predominant irritable bowel syndrome in Asia.
abstract: OBJECTIVE
  It has been reported that small intestinal bacterial overgrowth (SIBO) may lead to false positive diagnoses of lactose malabsorption (LM) in irritable bowel syndrome patients. The aim of this study was to determine the influence of SIBO on lactose hydrogen breath test (HBT) results in these patients.
  
  
  METHODS
  Diarrhea-predominant irritable bowel syndrome patients with abnormal lactose HBTs ingested a test meal containing (99m) Tc and lactose. The location of the test meal and the breath levels of hydrogen were recorded simultaneously by scintigraphic scanning and lactose HBT, respectively. The increase in hydrogen concentration was not considered to be caused by SIBO if ≥ 10% of (99m) Tc accumulated in the cecal region at the time or before of abnormal lactose HBT.
  
  
  RESULTS
  LM was present in 84% (31/37) of irritable bowel syndrome patients. Twenty of these patients agreed to measurement of oro-cecal transit time. Only three patients (15%) with abnormal lactose HBT might have had SIBO. The median oro-cecal transit time between LM and lactose intolerance patients were 75 min and 45 min, respectively (Z=2.545, P=0.011).
  
  
  CONCLUSIONS
  Most of irritable bowel syndrome patients with an abnormal lactose HBT had LM. SIBO had little impact on the interpretation of lactose HBTs. The patients with lactose intolerance had faster small intestinal transit than LM patients.
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Yilin
authors.initials: Y
authors.lastname: Wang
authors.forename: Lishou
authors.initials: L
authors.lastname: Xiong
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Gong
authors.forename: Weimin
authors.initials: W
authors.lastname: Li
authors.forename: Xiangsong
authors.initials: X
authors.lastname: Zhang
authors.forename: Minhu
authors.initials: M
authors.lastname: Chen
mesh_terms: D000328:Adult; D001208:Asia / Q000453:epidemiology; D001944:Breath Tests / Q000379:methods*; D003967:Diarrhea / Q000175:diagnosis* / Q000453:epidemiology* / Q000382:microbiology / Q000503:physiopathology; D005189:False Positive Reactions; D005260:Female; D005772:Gastrointestinal Transit; D006801:Humans; D006859:Hydrogen; D007421:Intestine, Small / Q000382:microbiology*; D043183:Irritable Bowel Syndrome / Q000175:diagnosis* / Q000453:epidemiology* / Q000382:microbiology / Q000503:physiopathology; D007785:Lactose; D007787:Lactose Intolerance / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D013997:Time Factors; D055815:Young Adult
chemical_list: D006859:Hydrogen; D007785:Lactose
keywords: irritable bowel syndrome; lactose intolerance; lactose malabsorption; scintigraphy