Bile acid diarrhea common in functional bowel disorder with diarrhea

Last Updated: 2015-10-06

By Will Boggs MD

NEW YORK (Reuters Health) - About one in four patients who have functional bowel disorders with diarrhea will have evidence of bile acid diarrhea, according to a systematic review.

"All patients who do not respond optimally to first-line, non-specific treatment of IBS-D/functional diarrhea should be tested for bile acid diarrhea, and if identified, treated with more specific therapy directed at the bile acid diathesis," Dr. Michael Camilleri from Mayo Clinic in Rochester, Minnesota, told Reuters Health by email.

Several studies have documented bile acid diarrhea in patients with chronic diarrhea or diarrhea-predominant irritable bowel syndrome (IBS-D), but the prevalence of bile acid diarrhea in patients with IBS-D or functional diarrhea is unclear.

Dr. Camilleri and colleagues evaluated the diagnostic yield of several biomarkers for bile acid diarrhea in their systematic review and meta-analysis of 36 studies.

Twenty-four studies measured 75SeHCAT retention of less than 10%, six studies measured serum C4, three measured serum FGF19, and two measured total fecal bile acid in 48 hours. The researchers defined diagnostic yield as the percentage of subjects with a confirmed diagnosis of IBS-D or functional diarrhea who tested positive for idiopathic bile acid diarrhea.

75SeHCAT had the highest diagnostic yield, at 30.8%, followed by total fecal bile acids at 48 hours (25.5%), fasting serum FGF19 (24.8%), and serum C4 (17.1%). There was considerable variability across the studies, the researchers report in Gut online September 7.

"Though some studies suggested there would be a high rate, we were surprised that with the 4 different methods, in a large number of studies from all over the world, there was a uniform answer, that is, that about a quarter or a third of patients with unexplained diarrhea had evidence of bile acid diarrhea," Dr. Camilleri said.

"In the future, it is hoped that laboratory medicine will offer more convenient screening tests for bile acid diarrhea including fasting blood sample for serum C4 and serum FGF19," Dr. Camilleri said. "If clinicians screen for coeliac disease in patients with unexplained diarrhea, they should also start screening for bile acid diarrhea in the same patient group."

The researchers note, "75SeHCAT is not available in the USA and many other countries; hence, the development of alternative diagnostic tests to identify idiopathic bile acid diarrhea in clinical practice is important."

Dr. Adam Farmer from Wingate Institute of Neurogastroenterology in London, UK, told Reuters Health by email, "We have recently published a meta-analysis examining the rates of bile acid diarrhea in patients with Rome-defined IBS with diarrhea. We found that rates of bile acid malabsorption in this group were 28.1%. This is not a trivial number as such patients respond well to bile acid sequestrants."

"These findings are very important, particularly in the context that 75SeHCAT testing in not widely available in the US," he said. "Thus many patients are never diagnosed. A common strategy in clinical practice is to give patients a therapeutic trial of cholestyramine, which is not very palatable to take. Thus patients do not take the medication and do not experience an improvement in symptoms, and this is frequently erroneously interpreted by the physician as a negative response and thus not bile acid diarrhea."

Dr. Farmer added, "Both this paper and ours also raise the issue regarding interpretation of previous clinical trials and research in IBS-D - if approximately 30% of patients in these studies did not have IBS-D ab initio then how can we reliably interpret the results? Moreover, I think it has further implications for the Rome diagnostic criteria, and I believe that a negative 75SeHCAT should be included in the new guidelines."

SOURCE: http://bit.ly/1FRCVIi

Gut 2015.