title: Abnormal breath tests to lactose, fructose and sorbitol in irritable bowel syndrome may be explained by small intestinal bacterial overgrowth.
abstract: BACKGROUND
  Small intestinal bacterial overgrowth and sugar malabsorption (lactose, fructose, sorbitol) may play a role in irritable bowel syndrome. The lactulose breath test is a reliable and non-invasive test for the diagnosis of small intestinal bacterial overgrowth. The lactose, fructose and sorbitol hydrogen breath tests are widely used to detect specific sugar malabsorption.
  
  
  OBJECTIVE
  To assess the extent to which small intestinal bacterial overgrowth may influence the results of hydrogen sugar breath tests in irritable bowel syndrome patients.
  
  
  METHODS
  We enrolled 98 consecutive irritable bowel syndrome patients. All subjects underwent hydrogen lactulose, lactose, fructose and sorbitol hydrogen breath tests. Small intestinal bacterial overgrowth patients were treated with 1-week course of antibiotics. All tests were repeated 1 month after the end of therapy.
  
  
  RESULTS
  A positive lactulose breath test was found in 64 of 98 (65%) subjects; these small intestinal bacterial overgrowth patients showed a significantly higher prevalence of positivity to the lactose breath test (P < 0.05), fructose breath test (P < 0.01) and sorbitol breath test (P < 0.01) when compared with the small intestinal bacterial overgrowth-negatives. Small intestinal bacterial overgrowth eradication, as confirmed by negative lactulose breath test, caused a significant reduction in lactose, fructose and sorbitol breath tests positivity (17% vs. 100%, 3% vs. 62%, and 10% vs. 71% respectively: P < 0.0001).
  
  
  CONCLUSIONS
  In irritable bowel syndrome patients with small intestinal bacterial overgrowth, sugar breath tests may be falsely abnormal. Eradication of small intestinal bacterial overgrowth normalizes sugar breath tests in the majority of patients. Testing for small intestinal bacterial overgrowth should be performed before other sugar breath tests tests to avoid sugar malabsorption misdiagnosis.
authors.affiliation: Internal Medicine Department, Gemelli Hospital, Catholic University of Sacred Heart, Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Nucera
authors.forename: M
authors.initials: M
authors.lastname: Gabrielli
authors.forename: A
authors.initials: A
authors.lastname: Lupascu
authors.forename: E C
authors.initials: EC
authors.lastname: Lauritano
authors.forename: A
authors.initials: A
authors.lastname: Santoliquido
authors.forename: F
authors.initials: F
authors.lastname: Cremonini
authors.forename: G
authors.initials: G
authors.lastname: Cammarota
authors.forename: P
authors.initials: P
authors.lastname: Tondi
authors.forename: P
authors.initials: P
authors.lastname: Pola
authors.forename: G
authors.initials: G
authors.lastname: Gasbarrini
authors.forename: A
authors.initials: A
authors.lastname: Gasbarrini
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents; D001424:Bacterial Infections / Q000150:complications* / Q000188:drug therapy / Q000378:metabolism; D001944:Breath Tests; D003951:Diagnostic Errors; D004359:Drug Therapy, Combination / Q000627:therapeutic use; D005189:False Positive Reactions; D005260:Female; D005632:Fructose / Q000032:analysis*; D006801:Humans; D007421:Intestine, Small / Q000378:metabolism / Q000382:microbiology; D043183:Irritable Bowel Syndrome / Q000378:metabolism / Q000382:microbiology*; D007785:Lactose / Q000032:analysis*; D008286:Malabsorption Syndromes / Q000175:diagnosis*; D008297:Male; D013012:Sorbitol / Q000032:analysis*
chemical_list: D000900:Anti-Bacterial Agents; D005632:Fructose; D013012:Sorbitol; D007785:Lactose