Functional Diarrhea
This care pathway can be used to guide primary care providers in the management of patients with functional diarrhea. This pathway was developed by the specialists at GI Motility Clinic at the Toronto Western Hospital and follows the Rome IV criteria for functional diarrhea.
SUMMARY OF FUNCTIONAL DIARRHEA
Functional diarrhea (FDr) is a disorder of the gut-brain interaction (DGBI) in which the symptoms are characterized by recurrent passage of loose or watery stools without evidence of structural, infectious, or metabolic abnormalities. Patients with FDr may have rare abdominal pain and/or bloating, but they are not predominant symptoms such as seen in patients with irritable bowel syndrome (IBS).
​
The prevalence of FDr has been poorly investigated, and the only significant risk factor is prior infectious gastroenteritis.
Diagnosing FDr is based on clinical history, physical examination, and limited diagnostic tests. IBS must be excluded. Stool consistency rather than frequency or the presence of urgency is used to define FDr. The Bristol Stool Form Scale is useful for assessing stool form. The patient should be encouraged to keep a 7-day stool and diet diary using BSFS to document stool consistency.
ROME IV DIAGNOSTIC CRITERIA
FUNCTIONAL DIARRHEA
Loose or watery stools, without predominant abdominal pain or bothersome bloating, occurring more than 25% of stools.
​
Criteria fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis.
​
Patient does not meet the criteria for diarrhea-predominant irritable bowel syndrome.
PRIMARY CARE CHECKLIST
-
Detailed diarrhea history and physical examination
-
Absence of alarm features:
-
Anemia, iron deficiency, GI bleeding​
-
Sudden or progressive changes in bowel habits, nocturnal diarrhea
-
Fever, chills
-
Acute or intentional weight loss
-
New onset after the of 50
-
Positive family history of colorectal cancer
-
Celiac disease or inflammatory bowel disease
-
FIT positive, if done for screening purposes
-
Abnormality on physical examination
-
-
Exclude secondary causes for diarrhea (infection, recent antibiotic use, magnesium, supplements/antacids, prokinetics, metabolic causes, among others)​
-
Review dietary history, including any recent changes
-
Review travel history
-
Review medication history, including any recent changes
-
The patient meets the Rome IV diagnostic criteria for functional diarrhea
-
Baseline laboratory tests:
-
CBC, electrolytes, albumin, C-reactive protein, TSH, celiac disease (anti-tTG IgA), stool for C. difficile, culture & sensitivity, and ova parasite​
-
ALGORITHM FOR FUNCTIONAL DIARRHEA
Suspected Functional Diarrhea
Consider referral to GI
YES
ALARM FEATURES?
NO
History & physical assessment​
Rule out secondary causes
Review dietary history
Review travel history
Abnormal findings
Investigate and treat as appropriate
Complete baseline laboratory tests
Normal results
Abnormal results
Establish diagnosis for Functional Diarrhea
GENERAL PRINCIPLES FOR FUNCTIONAL DIARRHEA TREATMENT
​
Patient counselling and reassurance
Avoid triggers
Fiber supplementation
Stress reduction
No response
Initiate pharmacological treatment
Loperamide
No response
Cholestyramine 4 grams 1 to 2 times daily PRN
No response
Neuromodulators:
Desipramine 10 mg qHS
or
Amitriptyline 10 mg qHS
No response
Consider referral to GI
EXPLANATION OF ALGORITHM FOR FUNCTIONAL DIARRHEA
PHYSICAL & HISTORY ASSESSMENT
When diagnosing FDr, a careful diarrhea history and thorough abdominal and anorectal examination are recommended. Review the patient’s dietary history to exclude lactose and fructose malabsorption and excess fibre consumption. Review the patient’s travel history to areas with recognized specific diarrhea-related pathogens. Assess the patient’s medication list for drugs that may cause diarrheal symptoms. If possible, these medications should be discontinued or reduced. A careful anorectal examination is recommended to assess sphincter tone (especially for patients who report incontinence) and to identify a mass, fissure, or hemorrhoidal disease.
There should be limited use of diagnostic tests as it is a diagnosis based on clinical symptoms. Exclude alarm features as listed above. The presence of alarm features should prompt further investigation and/or consideration of a referral to a specialist.
​INVESTIGATIONS
Baseline laboratory tests to investigate FDr include CBC, electrolytes, and albumin. Patients reporting symptoms of chronic diarrhea (more than 4 weeks) should be screened for celiac disease (CD) and inflammatory bowel disease (IBD). An anti-tTG IgA is recommended to screen for CD, and a C-reactive protein, if elevated, may suggest systemic inflammation. It should be noted that a normal C-reactive protein does not rule out IBD.
Clinical history/physical examination should guide the need for further investigations to rule out IBD. A TSH may be helpful to determine hyperthyroidism. Stool for C. difficile, culture & sensitivity, and ova & parasite should be completed to exclude a possible infectious cause for diarrhea.
​​
GENERAL PRINCIPLES OF FUNCTIONAL DIARRHEA
Once a diagnosis for FDr has been established, counsel and reassure the patient about the benign nature of the condition. It is helpful to review the gut-brain axis to help the patient understand their condition and establish realistic treatment goals. Patients need to identify triggers for their diarrhea and avoid them if possible. Keeping a symptom diary can help patients understand factors that can provoke their symptoms.
Treatment response for FDr can vary, and it should be explained to the patient that a trial and error approach is frequently needed to find an individualized regimen. Ideally, a regimen should be trialled for eight weeks with a follow-up of treatment response.
​
Initial treatment for FDr should start with non-pharmacological interventions. If these interventions have a suboptimal response, discuss the addition of pharmacological treatments with the patient.
​
Identify Triggers
If the patient has food-related triggers and if it is appropriate, a referral to a Dietician to help with food elimination and diet modification may be helpful. Stress and anxiety can be triggers for FDr. Cognitive-behavioural therapy (CBT) and mindfulness-based therapy (MBT) have shown to be successful in managing other DGBI. They may be an option for patients willing to participate in therapy. There is evidence of enhanced symptom relief when CBT or MBT are combined with low-dose neuromodulators (see below).
Fibre Supplementation
For patients with small volume, watery diarrhea or fecal incontinence, supplementation with soluble fibres can increase stool bulk to improve stool consistency. Sources of soluble fibres include psyllium (Metamucil®), guar gum (The Right Fibre4®), oatmeal, inulin (Benefibre®), citrus fruits, and oatmeal.
​
Pharmacological Treatment
Medication | Recommended Dose | Side Effects | Patient Education |
|---|