Prevalence of lactose malabsorption in Mexican children: importance of measuring methane in expired air.

BACKGROUND AND AIMS: To compare the prevalence of lactose malabsorption (LM) in children by analyzing hydrogen content in expired air vs. the inclusion of methane excretion.

METHODS

A total of 138 children (4-17 years old) attending different boarding schools in Mexico were included in this study. To measure H₂ and CH₄ in expired air, breath samples were collected before administering whole milk (240 mL for 4- to 6-year-old children and 360 mL for 7- to 17-year-old children) and at 60, 120, 180, and 240 min afterward. A coprological examination was also carried out.

RESULTS

Methane production prevalence was 47.8% (29.7% of the children produced methane and hydrogen, whereas 18.1% produced methane only). When measuring only exhaled hydrogen in expired air (H₂ ≥20 ppm), prevalence of LM was 31%; however, when methane concentration was considered (H₂ + (CH₄ x 2)) ≥18 ppm, prevalence increased significantly to 44%. Among children with LM, 51.6% presented intestinal parasites.

CONCLUSIONS

Methane should be measured in exhaled air to improve diagnosis of LM in populations with a high prevalence of methane production.