Hydrogen breath testing versus LCT genotyping for the diagnosis of lactose intolerance: a matter of age?

Clin Chim Acta. 2007 Aug;383(1-2):91-6. doi: 10.1016/j.cca.2007.04.028. Epub 2007 May 10.


Background: Two single nucleotide polymorphisms (-13910 C/T and -22018 G/A) upstream of the lactase gene (LCT) have been found to be associated with lactose tolerance in Europeans.

Methods: In one hundred and twenty Austrian outpatients, who visited the physician's office for symptoms of irritable bowel syndrome (IBS), hydrogen breath testing (HBT) and LCT genotyping by polymerase chain reaction and reverse-hybridisation were performed in parallel.

Results: The coincidence between a genotype suggesting lactase non-persistence (lactose intolerance) and a positive HBT result was almost perfect (97.4% for LCT-13910 C/T and 100% for LCT-22018 G/A). Between a genotype indicating lactase persistence (lactose tolerance) and a negative HBT result the coincidence was lower (72% and 71.4%, respectively). Among heterozygotes, there was a statistically significant increase in the proportion of positive HBT results with age. Both SNPs were in accordance in 117/120 (97.5%) patients.

Conclusion: Genetic analysis of LCT-13910 C/T and LCT-22018 G/A is a good indicator for the presence of lactose intolerance. Because age, as well as a number of secondary causes (e.g. celiac disease), can influence HBT results, it is useful to combine HBT and genetic analysis in the diagnostic assessment of IBS.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Aged
  • Aged, 80 and over
  • Austria
  • Breath Tests / methods*
  • Child
  • Diagnostic Errors
  • Female
  • Genetic Testing / methods
  • Genetic Testing / standards*
  • Genotype
  • Humans
  • Hydrogen / analysis*
  • Lactase / genetics*
  • Lactose Intolerance / diagnosis*
  • Male
  • Middle Aged
  • Polymorphism, Single Nucleotide
  • Reproducibility of Results


  • Hydrogen
  • Lactase