Unreliability of Breath Methane as a Candidate Indicator of Functional Bowel Disorders

Jonderko, Krzysztof; Gabriel-Jasniok, Agata; Szymszal, Malgorzata; Kasicka-Jonderko, Anna; Blonska-Fajfrowska, Barbara

Abstract

BACKGROUND/AIMS: The aim of this study was to examine the reproducibility of methane and hydrogen in exhaled air breath after a per-oral load of lactulose.
METHODS
Methane was present in the exhaled breath of 21 of 50 healthy subjects recruited by advertisement. Three methane breath tests were performed in 12 women (aged 23.6+/-0.5 years, mean+/-SEM) after they consumed 10 g of lactulose dissolved in 300 ml of water. Short- and medium-term reproducibilities were assessed by paired examinations taken 3 and 17 days (median) apart, respectively.
RESULTS
High values of coefficients of variation for paired examinations (CV(p)) indicated a poor short-term reproducibility of parameters characterizing either the methane or hydrogen excretion in breath air: CV(p) values of the maximum net increments over baseline in methane (max CH4_net), and in hydrogen (max H2_net), were 34% and 41%, respectively. Moreover, the reproducibility consistently deteriorated with increasing time gap between repeat measurements (CV(p): 60% for max CH4_net and 64% for max H2_net).
CONCLUSIONS
The low reproducibility of parameters characterizing quantitative methane breath excretion suggests that caution is necessary when judging the clinical usefulness of the methane breath test after a per-oral lactulose load for the purpose of diagnosing and classifying functional bowel disorders.