Bethesda, MD (Sept. 23, 2019)-- Diagnosing patients with chronic watery diarrhea can be difficult for health care providers, since several causes with specific therapies, such as inflammatory bowel disease (IBD), microscopic colitis and chronic infection, need to be ruled out. A new clinical guideline1 (superscript 1) from the American Gastroenterological Association (AGA) published in Gastroenterology, the official journal of the AGA Institute, provides recommendations on the appropriate laboratory tests based on current evidence to exclude other diagnoses in the setting of suspected functional diarrhea or irritable bowel syndrome with diarrhea (IBS-D).
"When managing patients with chronic watery diarrhea, it is important for health care providers to determine whether it is being caused by organic disease or a functional disorder, such as functional diarrhea or irritable bowel syndrome with diarrhea," said Walter Smalley, MD, MPH, first author, Veterans Affairs Tennessee Valley Healthcare System and Vanderbilt University School of Medicine, Nashville, Tennessee. "Both functional diarrhea and IBS-D are clinical diagnoses with no defining laboratory tests. A workup to exclude all organic disease is impractical, expensive and potentially dangerous to patients if false-positive tests result in further invasive testing. The AGA guideline on evaluation of chronic diarrhea is intended to reduce practice variation and promote high-quality and high-value care for this patient population."
The AGA guideline applies to patients with properly working immune systems who have "watery" diarrhea of at least four weeks duration. It excludes patients with bloody diarrhea; diarrhea with signs of poor fat absorption; features of alarm symptoms, such as weight loss, anemia and hypoalbuminemia; a family history of IBD, colon cancer or celiac disease; and those with a travel history to regions where diarrhea-related diseases are common.
The guideline recommends considering the use of the following laboratory tests for the evaluation of functional diarrhea and IBS-D in adults:
- 1. In patients presenting with chronic diarrhea, AGA suggests the use of either fecal calprotectin or fecal lactoferrin, which have been proposed as markers for inflammatory conditions, such as IBD. (Conditional recommendation; low quality evidence)
2. In patients presenting with chronic diarrhea, AGA suggests against the use of erythrocyte sedimentation rate or C-reactive protein to screen for IBD. (Conditional recommendation: low evidence)
3. In patients presenting with chronic diarrhea, AGA recommends testing for Giardia, a common cause of watery diarrhea that can be readily treated. (Strong recommendation: high quality evidence)
4. In patients presenting with chronic diarrhea with no travel history to or recent immigration from high risk areas, AGA suggests against testing for ova and parasites (other than Giardia). (Conditional recommendation: low quality evidence)
5. In patients presenting with chronic diarrhea, AGA recommends testing for celiac disease with IgA tissue transglutaminase and a second test to detect celiac disease in the setting of IgA deficiency. Celiac disease is an important cause of chronic diarrhea. (Strong recommendation: moderate quality evidence)
6. In patients presenting with chronic diarrhea, AGA suggests testing for bile acid diarrhea, which may be due to excess production or decreased absorption of bile acids, which then reach the colon and can cause watery diarrhea. (Conditional recommendation: low quality evidence)
7. In patients presenting with chronic diarrhea, AGA makes no recommendation for the use of currently available serologic tests for diagnosis of IBS. (No recommendation; knowledge gap)
Read the AGA Clinical Practice Guidelines on the Laboratory Evaluation of Functional Diarrhea and Diarrhea-Predominant Irritable Bowel Syndrome in Adults (IBS-D) to review the complete recommendations.
What is diarrhea and IBS-D?
Diarrhea happens when a patient has loose, watery stools three or more times a day. When diarrhea lasts four weeks or more, it is considered chronic, or long-term, diarrhea. While diarrhea is a common health problem, impacting 179 million people in the US a year, it can also be associated with a health condition called irritable bowel syndrome (IBS), a common disorder of the large intestine.
There are different types of IBS -- IBS-D: IBS with diarrhea; IBS-C: IBS with constipation; IBS-M: IBS mixed. General symptoms for all types can include belly pain, cramping in the stomach area, gas, bloating and changes in the stool, such as diarrhea, constipation or an urgent need to go. IBS impacts about 35 million Americans, physically, emotionally and socially.
Resources for health care providers
- Technical review: Evaluation of functional diarrhea and IBS-D
- Clinical decision support tool: IBS-D in adults
- Spotlight: Laboratory evaluation of functional diarrhea and IBS-D in adults
- AGA University education: Laboratory evaluation of functional diarrhea and IBS-D
Resources for patients
- Patient summary: AGA clinical practice guidelines on the laboratory evaluation of functional diarrhea and IBS-D
- AGA patient education: IBS
1 Smalley, W., Falck-Ytter, C., Carrasco-Labra, A., Wani, S., Lytvyn, L., Falck-Ytter, Y. AGA Clinical Practice Guidelines on the Laboratory Evaluation of Functional Diarrhea and Diarrhea-Predominant Irritable Bowel Syndrome in Adults (IBS-D) (2019). DOI: https:/
2 Carrasco-Labra, A., Lytvyn, L., Falck-Ytter, Y., Surawicz, C.M., Chey, W.D. AGA Technical Review on the Evaluation of Functional Diarrhea and Diarrhea-Predominant Irritable Bowel Syndrome in Adults (IBS-D) (2019). DOI: https:/
Media contact: Lucia Allen, firstname.lastname@example.org, 301-272-1608
About the AGA Institute
The American Gastroenterological Association is the trusted voice of the GI community. Founded in 1897, the AGA has grown to include more than 16,000 members from around the globe who are involved in all aspects of the science, practice and advancement of gastroenterology. The AGA Institute administers the practice, research and educational programs of the organization. http://www.
Gastroenterology, the official journal of the AGA Institute, is the most prominent scientific journal in the specialty and is in the top 1 percent of indexed medical journals internationally. The journal publishes clinical and basic science studies of all aspects of the digestive system, including the liver and pancreas, as well as nutrition. The journal is abstracted and indexed in Biological Abstracts, Current Awareness in Biological Sciences, Chemical Abstracts, Current Contents, Excerpta Medica, Index Medicus, Nutrition Abstracts and Science Citation Index. For more information, visit http://www.
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