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 (CH(4)) during a lactose test. The aim of this study is to evaluate the contribution of CH(4) measurements. We tested 209 children (1–17 years old) with symptoms suggesting LI with lactose H(2) and CH(4) breath tests. The result was positive when the H(2) excretion exceeded 20 parts per million (ppm) and the CH(4) 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 CH(4); 96/209 (46%) had a positive H(2) breath test result; 31/96 (32%) were also positive for CH(4); 12/209 (6%) patients were only positive for CH(4). The majority of hydrogen producers showed symptoms, whereas this was only the case in half of the H(2)-negative CH(4) producers. Almost all patients treated with a lactose-poor diet reported significant symptom improvement. These results indicate that CH(4) 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 CH(4), and half of them experienced symptoms during the test.