Additional Value of CH₄ Measurement in a Combined (13)C/H₂ Lactose Malabsorption Breath Test: A Retrospective Analysis

Nutrients. 2015 Sep 7;7(9):7469-85. doi: 10.3390/nu7095348.


The lactose hydrogen breath test is a commonly used, non-invasive method for the detection of lactose malabsorption and is based on an abnormal increase in breath hydrogen (H₂) excretion after an oral dose of lactose. We use a combined (13)C/H₂ lactose breath test that measures breath (13)CO₂ as a measure of lactose digestion in addition to H₂ and that has a better sensitivity and specificity than the standard test. The present retrospective study evaluated the results of 1051 (13)C/H₂ lactose breath tests to assess the impact on the diagnostic accuracy of measuring breath CH₄ in addition to H₂ and (13)CO₂. Based on the (13)C/H₂ breath test, 314 patients were diagnosed with lactase deficiency, 138 with lactose malabsorption or small bowel bacterial overgrowth (SIBO), and 599 with normal lactose digestion. Additional measurement of CH₄ further improved the accuracy of the test as 16% subjects with normal lactose digestion and no H₂-excretion were found to excrete CH₄. These subjects should have been classified as subjects with lactose malabsorption or SIBO. In conclusion, measuring CH₄-concentrations has an added value to the (13)C/H₂ breath test to identify methanogenic subjects with lactose malabsorption or SIBO.

Keywords: breath test; hydrogen; lactase deficiency; lactose malabsorption; methane; stable isotopes.

Publication types

  • Comparative Study
  • Evaluation Study

MeSH terms

  • Adolescent
  • Adult
  • Biomarkers / metabolism
  • Blind Loop Syndrome / diagnosis*
  • Blind Loop Syndrome / metabolism
  • Blind Loop Syndrome / physiopathology
  • Breath Tests*
  • Carbon Dioxide / metabolism*
  • Digestion
  • Female
  • Humans
  • Hydrogen / metabolism*
  • Lactose / metabolism
  • Lactose Intolerance / diagnosis*
  • Lactose Intolerance / metabolism
  • Lactose Intolerance / physiopathology
  • Male
  • Methane / metabolism*
  • Middle Aged
  • Predictive Value of Tests
  • Reproducibility of Results
  • Retrospective Studies
  • Young Adult


  • Biomarkers
  • Carbon Dioxide
  • Hydrogen
  • Lactose
  • Methane