Are hydrogen breath tests valid in the elderly?

Hydrogen breath testing (HBT) is frequently used as an alternative to small bowel aspiration in the diagnosis of small intestinal bacterial overgrowth (SIBO). The role of the glucose HBT was assessed in 30 elderly patients. A positive HBT was recorded in 15 of 20 SIBO cases and 7 of 10 culture negatives (sensitivity 75% and specificity 30%). The correlation coefficients between hydrogen gas (H2) rise and total bacterial count (r = 0.21) and H2 rise and anaerobic count (r = 0) were not significant. Fasting H2 levels were raised in only 4 of the 20 SIBO cases. This study indicates that the HBT is not reliable in the diagnosis of SIBO in the elderly. There was no evidence from the data that different H2 levels or bacterial counts would significantly alter the reliability of the HBT. This work suggests that factors other than small bowel bacteria are involved in the production and expiration of H2 in the elderly, and that these factors need to be considered in the interpretation of this breath test.