Correlation between symptoms developed after the oral ingestion of 50 g lactose and results of hydrogen breath testing for lactose intolerance

Aliment Pharmacol Ther. 2008 Apr;27(8):659-65. doi: 10.1111/j.1365-2036.2008.03623.x. Epub 2008 Jan 22.


Background: Lactase deficiency is a common condition responsible for various abdominal symptoms. Lactose hydrogen breath test is currently the gold standard in diagnosing lactose intolerance.

Aim: To assess sensitivity and specificity of symptoms developed after oral lactose challenge.

Methods: Intensity of nausea, abdominal pain, borborygmi, bloating and diarrhoea was recorded every 15 min up to 3 h after ingestion of 50 g lactose in patients with positive (i.e. breath H2-concentration > or =20 p.p.m. above baseline) and negative lactose hydrogen breath test.

Results: Between July 1999 and December 2005, 1127 patients (72% females) underwent lactose hydrogen breath test. A positive result was found in 376 (33%). Sensitivity of individual symptoms ranged from 39% (diarrhoea) to 70% (bloating) while specificity ranged from 69% (bloating) to 90% (diarrhoea). A positive lactose hydrogen breath test was found in 21% of patients with one symptom, 40% of patients with two symptoms, 44% of patients with three symptoms, 67% of patients with four symptoms and 82% of patients with five symptoms. Symptom intensity was significantly higher for each symptom in the positive group.

Conclusion: Evaluating symptoms developed after ingestion of 50 g lactose can be used as a simple screening test to select patients who need to be referred for lactose intolerance testing.

Publication types

  • Evaluation Study

MeSH terms

  • Administration, Oral
  • Adult
  • Breath Tests / methods
  • Female
  • Humans
  • Hydrogen / analysis*
  • Lactose
  • Lactose Intolerance / diagnosis*
  • Male
  • Prospective Studies
  • Sensitivity and Specificity


  • Hydrogen
  • Lactose