I admit I have not heard of hydrogen breath test, I will ask my GI about it. (perfecthealthdiet.com)
Specifically, the study had 25 patients undergo hydrogen breath testing after drinking a variety of solutions. (verywellhealth.com)
This update also added and clarified in the SUMMARY section: «the British Dietetic Association 2016 update for IBS recommends a trial period of a low lactose diet where sensitivity to milk is suspected and a lactose hydrogen breath test is not available or appropriate. (biomeonboardawareness.com)