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Arch Med Res. 2013 May;44(4):291-5. doi: 10.1016/j.arcmed.2013.04.005. Epub 2013 May 2.

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

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  • 1Laboratory of Gastro-Hepatology Research and Department of Nutrition, Hospital de Pediatría, Centro Médico Nacional, Instituto Mexicano del Seguro Social, México City, Mexico.



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


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.


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.


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

Copyright © 2013 IMSS. Published by Elsevier Inc. All rights reserved.

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