New guideline provides recommendations for testing adults with suspected Functional Diarrhea or Diarrhea-Predominant Irritable Bowel Syndrome (USA)

https://www.jwatch.org/na49679/2019...rhea-and-diarrhea-predominant?ijkey=6rMYefjWM

Testing for Functional Diarrhea and Diarrhea-Predominant Irritable Bowel Syndrome

Charles J. Kahi, MD, MS reviewing Smalley W et al. Gastroenterology 2019 Jul 11

A new guideline provides recommendations for the laboratory evaluation of adults with suspected FD or IBS-D.

Sponsoring Organization: American Gastroenterological Association (AGA)

Background and Objective

Functional diarrhea (FD) and diarrhea-predominant irritable bowel syndrome (IBS-D) are highly prevalent disorders that can be difficult to distinguish from organic causes of chronic diarrhea (i.e., lasting >4 weeks) based on symptoms alone. Clinicians often use an array of biomarkers to assist diagnosis; however, there is little available guidance regarding the appropriate use of available diagnostic tests. This guideline provides evidence-based recommendations addressing these gaps.

Key Recommendations

• Test for celiac disease with immunoglobulin A (IgA) tissue transglutaminase. In the case of IgA deficiency, immunoglobulin G (IgG) tissue transglutaminase and IgG or IgA deaminated gliadin peptides can be measured.
  
  
• Test for Giardia infectionusing antigen test or polymerase chain reaction.
  
  
• Consider testing for bile acid diarrhea. If assays are unavailable, empiric treatment with a bile acid binder is reasonable.
  
  
• Use either fecal calprotectin (threshold, 50 μg/g) or fecal lactoferrin (threshold range, 4.0–7.25 μg/g) to screen for inflammatory bowel disease (IBD).
  
  
• Do not measure erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) to screen for IBD, although CRP can be considered as an alternative to fecal calprotectin or lactoferrin if these cannot be measured.
  
  
• Do not test for ova and parasites in the absence of a suggestive travel or immigration history.
  
  
• The routine measurement of serological markers of IBS (antibodies to cytolethal distending toxin B and the gut mucosal protein vinculin) awaits additional supportive data.

Comment

These guidelines are based on an informative technical review of each diagnostic test (Gastroenterology 2019 Jul 25; [e-pub]) and provide practical guidance for primary care and GI providers. Take-home points are to avoid the “kitchen sink” approach where multiple tests are done simultaneously in patients with suspected FD or IBS-D, and rather to focus first on celiac disease, Giardia infection, and stool inflammatory markers. An empiric trial of bile acid binders is a reasonable concomitant or subsequent step, as diagnostic tests for bile acid diarrhea are either not available or not widely used. Older patients with chronic watery diarrhea should be considered for endoscopic evaluation with biopsy to exclude microscopic colitis.

Note to readers: At the time we reviewed this paper, its publisher noted that it was not in final form and that subsequent changes might be made.

 

IMO do not test for ova or parasites...needs some clarification. Is this travel outside developed countries?

What about where water systems, even in cities in developed countries have boil water advisories, as we now have at least partly due to climate change. Perhaps patients with diarrhea who live in these areas should be tested for ova and parasites.

And, what about people who drink "wild water" during outdoor activities? If they end up with this problem, perhaps they should be tested.

IMHO this investigation re ova and parasites could start with these questions, or ones similar: do you live in a boil water advisory area, or have you visited one? Have you recently consumed any water
directly from streams, lakes, rivers - any untreated water?