Hydrogen and Methane Breath Test in the Diagnosis of Lactose Intolerance

The hydrogen (H-2) breath test is a non-invasive investigation used to diagnose lactose intolerance (LI). Patients with LI may also expire increased amounts of methane (CH4) during a lactose test. The aim of this study is to evaluate the contribution of CH4 measurements. We tested 209 children (1-17 years old) with symptoms suggesting LI with lactose H-2 and CH4 breath tests. The result was positive when the H-2 excretion exceeded 20 parts per million (ppm) and the CH4 was 10 ppm above the baseline. A clinician, blinded for the results of the breath test, registered the symptoms. Of the patient population, 101/209 (48%) were negative for both H-2 and CH4; 96/209 (46%) had a positive H-2 breath test result; 31/96 (32%) were also positive for CH4; 12/209 (6%) patients were only positive for CH4. The majority of hydrogen producers showed symptoms, whereas this was only the case in half of the H-2-negative CH4 producers. Almost all patients treated with a lactose-poor diet reported significant symptom improvement. These results indicate that CH4 measurements may possibly be of additional value for the diagnosis of LI, since 5.7% of patients were negative for H-2 and positive for CH4, and half of them experienced symptoms during the test.

Automated summary

The study found that measuring CH4 may contribute to the diagnosis of lactose intolerance, with a portion of patients being negative for H-2 but positive for CH4 and experiencing symptoms.