Relevance of Methane and Carbon Dioxide Evaluation in Breath Tests for Carbohydrate Malabsorption in a Paediatric Cohort

Abstract

Objectives: The relevance of methane measurement in breath tests for the detection of carbohydrate malabsorption in children is controversial. The need for correction for poor sample collection is disputed. We evaluated the relevance of methane/CO2 measurements for the diagnosis of paediatric carbohydrate malabsorption. Methods: A total of 132 breath tests (fructose: n = 54; lactose: n = 78) were performed in 91 children/adolescents with functional abdominal complaints. Breath samples were collected and analysed for hydrogen, methane, and CO2. Malabsorption was defined by a net increase over baseline of ≥20 parts per million (ppm) for hydrogen, ≥5 to ≥12 ppm for methane, and ≥10 to ≥15 ppm for hydrogen-plus-methane. The diagnosis was made before and after the use of a CO2-based correction factor (5.5% as the numerator). Hydrogen-based test results were compared with results obtained with other cut-off values. Results: Fifty-eight positive tests were obtained by hydrogen measurement (without CO2 correction). The addition of methane measurements did not significantly influence the test results (P > 0.05). Only under the use of extraordinary cut-offs (combined hydrogen-plus-methane smaller than ≥18 ppm) did the rate of malabsorbers increase significantly (P < 0.05). After CO2 correction, hydrogen ≥20 ppm was detected in 4 additional patients, but 1 patient lost the hydrogen-based diagnosis of malabsorption (Cohen kappa = 0.92). Conclusions: Methane measurement did not significantly affect the detection rate of carbohydrate malabsorbers in children/adolescents with functional abdominal complaints when established cut-offs are used. The use of CO2 correction altered the diagnosis of malabsorption in a minority of patients but did not significantly alter overall test results.

European guideline on indications, performance, and clinical impact of hydrogen and methane breath tests in adult and pediatric patients: European Association for Gastroenterology, Endoscopy and Nutrition, European Society of Neurogastroenterology and Motility, and European Society for Paediatric Gastroenterology Hepatology and Nutrition consensus

“…Some breath test analyzers use algorithms based on the measurement of CO 2 or O 2 in exhaled air to correct for dead space air in the breath samples. However, the detection rate of carbohydrate malabsorption has not been significantly affected by additional measurement of CH 4 or of CO 2 in children and adolescents 62 . The potential increase in test accuracy due to these additional measurements must be weighed up against higher costs of equipment and potentially more complicated breath collection.…”

“…and therefore not applicable to all pediatric patients, 109,[147][148][149] and the diagnostic gain of additional CH 4 -measurement over measurement of H 2 alone in children and adolescents is disputed. 62…”

Delayed Analysis of Hydrogen-Methane Breath Samples

“…Regardless of whether the additional determination of CH 4 levels is clinically relevant or not, the overall detection rate of carbohydrate malabsorption is not significantly affected by additional measurements of CH 4 [ 5 17 ]. The possible increase in test accuracy related to this extra measurement must be weighed against the increased costs of equipment and more complex breath collection.…”

Hydrogen and Methane Breath Test in the Diagnosis of Lactose Intolerance

“…Therefore, a threshold of 3 ppm was proposed [ 27 ]. Others proposed a threshold of 10 ppm [ 19 , 23 ], and in a recent study by Hammer et al [ 28 ], malabsorption was defined by a net increase of ≥5 to ≥12 ppm for CH 4 , and ≥10 to ≥15 ppm for H 2 plus CH 4 . In our group, 25% of the children showed elevated CH 4 excretion of more than 10 ppm.…”

“…It was stated that patients usually produce either H 2 or CH 4 , and only rarely produce both [ 25 ]. Hammer et al [ 28 ] also found that the addition of CH 4 hardly influenced the results of malabsorption, and only under the use of specific cut-offs (the combined rise in H 2 and CH 4 should be less than 18) was a significant increase in the rate of malabsorbers seen. However, in our study, most of the CH 4 -positive tests (72%) were found in the children that also demonstrated a positive H 2 breath test.…”