Burping baby? A 4-year-old with a chronic stomachache? Thinking of lactose-intolerance? The lactose hydrogen breath test (HBT) is an inventive, non-invasive way to detect a low lactase. All your patient needs to do is take a deep breath and allow you to collect some exhaled air. The test seems reliable too. It showed high sensitivity and specificity in previous research.¹
The lactose HBT measures hydrogen in exhaled breath, produced by metabolization of lactose in the so-called process of ‘colonic fermentation’. In the presence of sufficient lactase, lactose is absorbed in the duodenum. However, if there is little lactase in the duodenum (hypolactasia), lactose will be metabolized, or fermented, by the colon. A side product of this process is hydrogen, which is excreted via the lungs and detected by the lactose HBT. Colonic fermentation may be accompanied by stomach ache, flatulence and osmotic diarrhea. Despite promising test parameters, the relation between clinical signs of lactose-intolerance and test results proves poor. This mismatch arises because hypolactasia in children is rare. All babies are born with the capability to metabolize lactose in breast
milk. Above the age of 2, this capability decreases, but only slowly. If hypolactasia does occur, this will only cause symptoms in a small group of patients with excessive lactose intake or comorbid gastro-intestinal disease. Thus, hydrogen breath testing has a very limited clinical use. Rather try if it is helpful to limit lactose intake, or search for another explanation for the gastro-intestinal symptoms.²
R.A.L. Beekman & M. Bijlsma
- Usai-Satta P et all. Lactose malabsorption and intolerance: What should be the best clinical management? World J Gastrointest Pharmacol Ther. 2012 Jun 6; 3(3): 29–33.
- Bindels PJE. (2013). Kindergeneeskunde. 8.9 Lactosemalabsorptie en lactose-intolerantie. Houten: Bohn Stafleu van Loghum