Hydrogen breath


Expired air taken into syringe. The specimen must be collected by trained staff.


If done as part of a tolerance test the appropriate test material (eg, lactose) is given orally and specimens are collected for 3 hours.

Hydrogen is analysed by gas chromatography.

Reference Interval:

Varies with test material.


Not routinely available in each state. Investigation of malabsorption (especially lactose), small bowel bacterial overgrowth.


If malabsorption is present, breath hydrogen is increased following ingestion of the material.

If there is small bowel bacterial overgrowth, short small bowel, or hypermotility, hydrogen production commences earlier than normal.


Cash BD et al. Am J Gastroenterol. 2002; 97(11): 2812-2819.