[Influencing Factors on Lactulose Breath Test Results]

Korean J Gastroenterol. 2020 Jan 25;75(1):23-28. doi: 10.4166/kjg.2020.75.1.23.
[Article in Korean]


Background/aims: This study aimed to identify the demographic and clinical factors associated with positive breath-test results and to assess the relationship between hydrogen and methane production in patients with suspected irritable bowel syndrome (IBS).

Methods: The demographic and clinical factors of 268 patients with suspected IBS, who had undergone a lactulose breath test, were analyzed.

Results: Of 268 patients included in this study, 143 (53.4%) were females. The median age and BMI of the patients was 58.0 years (range, 18.0-80.0 years) and 22.5 kg/m2 (range, 14.4-34.3 kg/m2), respectively. A weak positive correlation was observed between the BMI and baseline hydrogen level (rho=0.134, p=0.031). Women were significantly more likely to show a ≥20 ppm increase in hydrogen within 90 min (early hydrogen increase, p=0.049), a ≥10 ppm increase in methane within 90 min (early methane increase, p=0.001), and a ≥10 ppm increase in methane between 90 min and 180 min (late methane increase, p=0.002) compared to men. The baseline hydrogen level was related to the baseline methane level (rho=0.592, p<0.001) and the maximal hydrogen level within 90 min was related to maximal methane level within 90 min (rho=0.721, p<0.001). Patients with an early hydrogen increase (43.8%) were more likely to show a positive result for an early methane increase compared to patients without an early increase in hydrogen (0%, p<0.001).

Conclusions: Women were associated with high rates of positive lactulose breath-test results. In addition, methane production was correlated with hydrogen production.

Keywords: Breath tests; Difference; Irritable bowel syndrome; Lactulose; sex.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Body Mass Index
  • Breath Tests / methods*
  • Female
  • Humans
  • Hydrogen / metabolism
  • Irritable Bowel Syndrome / diagnosis*
  • Irritable Bowel Syndrome / pathology
  • Logistic Models
  • Male
  • Methane / metabolism
  • Middle Aged
  • Odds Ratio
  • Sex Factors
  • Young Adult


  • Hydrogen
  • Methane