Breath testing useful for many gastrointestinal disorders

Last Updated: 2017-04-07

By Will Boggs MD

NEW YORK (Reuters Health) - Hydrogen and methane-based breath testing is useful in the evaluation of common gastrointestinal disorders, according to a new North American consensus statement.

"Previous European guidelines were published more than 8 years ago,” said Dr. Ali Rezaie of Cedars-Sinai Medical Center in Los Angeles, California.

“Since then there has been a dramatic surge in human microbiome research which has revolutionized our understanding of small intestinal bacterial overgrowth (SIBO) and gut microbiota,” he told Reuters Health by email. “These new data are reflected systematically and meticulously in the recent North American consensus statement.”

Dr. Rezaie and colleagues in the North American Consensus group on hydrogen and methane-based breath testing aimed “to provide easy-to-follow recommendations on preparation, substrate doses, indications, performance, and interpretation of breath testing for SIBO and fructose/lactose intolerance,” he said.

Their 26 recommendations covering these five domains appeared online March 21 in The American Journal of Gastroenterology.

For the performance of breath tests, the experts settled on doses of 10 g for lactulose, 75 g for glucose, 25 g for lactose, and 25 g for fructose. They suggest ruling out the presence of bacterial overgrowth before lactose or fructose breath testing, and they agree that fructose and lactose breath testing should be performed for at least three hours.

Dr. Rezaie described the group consensus for interpretation of breath testing: "While the gold standard for diagnosis of SIBO remains ‘>1000 cfu/mL of bacteria in small bowel aspiration’ via endoscopy, breath testing provides an inexpensive, useful, non-invasive and safe alternative to diagnose SIBO. A rise in hydrogen level of >= 20 part per million (ppm) by 90 minutes during lactulose or glucose breath testing is considered positive for hydrogen-predominant SIBO. Methane levels of >= 10 ppm are compatible with methane-predominant bacterial overgrowth. Similarly, a rise of 20 ppm or more in breath hydrogen during 3 hours of fructose or lactose breath testing is considered a positive test.”

Appropriate indications for breath testing include possible SIBO, carbohydrate maldigestion, methane-associated constipation, and evaluation of bloating/gas, but it is not useful for the assessment of orocecal transit.

The consensus statement also points to more than a dozen gaps in knowledge and technology that require further clarification.

“The main goal of the current evidence-based consensus statement is to standardize breath testing in clinical practice and ultimately enhance quality of patient care,” Dr. Rezaie concluded. “Furthermore, the identified gaps of knowledge will direct future research initiatives and lay the ground work for future guidelines.”

Chu K. Yao, an accredited dietitian and PhD candidate at Monash University and Alfred Hospital in Melbourne, Australia, who recently reported poor reproducibility and low predictive value of lactulose and fructose breath tests in functional bowel disorder patients, said, “The diagnosis of SIBO based on a lactulose or glucose (and their suggested criteria) breath test is highly controversial. Several studies have shown that the results of these tests are poorly specific and highly variable between testing.”

“The recommendation of having breath testing for diagnosing fructose or lactose malabsorption is increasingly becoming less relevant in the management of patients with irritable bowel syndrome, with or without SIBO,” Yao told Reuters Health by email.

She added that although “there is a need to standardize recommendations for breath testing,” the evidence base for the consensus statement is “weak,” in particular regarding “indications for testing and interpretation of these tests.”

Yao said of the authors, “They also do not adequately highlight that there are major issues in the performance and interpretation of breath testing in clinical practice.”

SOURCE: http://bit.ly/2o5jiG2

Am J Gastroenterol 2017.