Management of Chronic Diarrhea

Diagnostic Evaluation

The American Gastroenterological Association recommends awaiting the pending Giardia EIA and ova/parasite results before proceeding with further invasive testing, as Giardia is the most common parasitic cause of chronic diarrhea and testing for it is strongly recommended in all patients with chronic diarrhea 1, 2, 3
Giardia testing is a strong recommendation with high-quality evidence for all patients presenting with chronic diarrhea, as it is the most common parasitic cause (prevalence 54% among identified parasites in chronic diarrhea) 2
Enzyme immunoassay (EIA) tests for Giardia have excellent diagnostic performance with sensitivity and specificity >95%, according to the American Gastroenterological Association 4
If the initial ova/parasite examination is negative but clinical suspicion remains high, molecular testing should be pursued, as recommended by the American Gastroenterological Association 2

The American Gastroenterological Association recommends considering empiric antiparasitic treatment with albendazole 400 mg plus ivermectin 200 μg/kg as a single dose for possible undetected geohelminth infections, particularly if there is a history of travel to or residence in endemic areas 5
The American Gastroenterological Association suggests considering an empiric trial of bile acid binders (cholestyramine or colesevelam) if testing for bile acid diarrhea is unavailable, with clinical response suggesting bile acid diarrhea as the cause 3

The American Gastroenterological Association recommends ordering fecal calprotectin or fecal lactoferrin to screen for inflammatory bowel disease (IBD), as this is recommended with conditional evidence for patients with chronic diarrhea 1, 3, 6
The American Gastroenterological Association suggests considering testing for bile acid diarrhea (BAD), as it is frequently overlooked and has a prevalence of 9.9%-35.3% in patients with IBS-D 2, 3

The American Gastroenterological Association recommends that colonoscopy is NOT indicated at this time given the patient's young age (<45 years), typical IBS-D symptoms, and absence of alarm features 7, 8, 6
The American Gastroenterological Association suggests that if fecal calprotectin is elevated, then colonoscopy with biopsies should be performed to evaluate for microscopic colitis or IBD 8

The American Gastroenterological Association recommends considering rifaximin 550 mg three times daily for 14 days to treat global IBS-D symptoms, as this is recommended with strong evidence [6, @10@]
Loperamide can be used for symptomatic control of diarrhea while awaiting diagnostic results, according to the American Gastroenterological Association [6, @10@]

Chronic Giardia infection can persist for months in individuals with impaired cell‑mediated immunity (e.g., immunocompromised patients), underscoring the need for prolonged monitoring and potentially extended therapy 9