Chronic diarrhea resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mugilan Poongkunran M.B.B.S [2]

Definition

Diarrhea is defined based upon the frequency, volume, and consistency of stools. It is more commonly defined as more than three loose stools in 24 hours or when the stool weight is more than 200 g per 24 hours containing more than 200 ml fluid per 24 hours. Chronic diarrhea is defined as a decrease in fecal consistency with or without increased stool frequency for more than 4 weeks. Chronic diarrhea may be divided into watery, fatty (malabsorption), and inflammatory (with blood and pus). Watery diarrhea may be subdivided into osmotic (water retention due to poorly absorbed substances), secretory (reduced water absorption), and functional (hypermotility) types. However, not all chronic diarrhea is strictly classified, because some categories overlap.

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

• Human immunodeficiency virus
• Inflammatory bowel disease

Common Causes

Fatty Diarrhea

• Malabsorption syndrome : Bacterial overgrowth, celiac disease, pancreatic insufficiency, short bowel resection, Whipple disease

Inflammatory Diarrhea

• Infection : Amebiasis, Cytomegalovirus, Strongyloides, Tuberculosis, Yersiniosis etc.
• Inflammatory bowel disease
• Ischemic colitis
• Neoplasia : Colon cancer, lymphoma
• Radiation enteritis

Osmotic Diarrhea

• Lactose intolerance
• Other : Antacids, fructose, lactulose, laxatives, magnesium, phosphate, sorbitol ingestion.

Secretory Diarrhea

• Bacterial toxins
• Hormonal : Carcinoid syndrome, diabetes, gastrinoma, hyperthyroidism, medullary carcinoma of thyroid, somatostatinoma, VIPoma
• Irritable bowel syndrome
• Medications : Angiotensin receptor blockers, antibiotics, chemotherapy, colchicine, H2-receptor antagonist, NSAIDs, proton pump inhibitors, SSRIs, laxative (nonosmotic laxatives) etc.
• Postsurgical : Cholecystectomy, gastrectomy, intestinal resection, vagotomy

Management

Adults with chronic diarrhea (> 4 weeks)

Characterize the symptoms: ❑ Onset (congenital, abrupt or gradual) ❑ Pattern (continuous or intermittent) ❑ Duration ❑ Stool characteristics (watery, bloody or fatty) ❑ Fever ❑ Abdominal pain ❑ Weight loss ❑ Fecal incontinence Obtain a detailed history: ❑ Aggravating factors (diet or stress) ❑ Over-the-counter drugs or use of prescription ❑ Previous evaluations (objective records, radiograms or biopsy specimens) ❑ Radiation therapy or surgery ❑ Factitious diarrhea (eating disorders, laxative ingestion, secondary gain or malingering) ❑ Systemic disease (cancer, diabetes, HIV, hyperthyroidism) Elicit the epidemiological factors: ❑ Travel before the onset of illness ❑ Exposure to contaminated food or water ❑ Illness in other family members

Examine the patient: Assess the volume status: ❑ General condition ❑ Thirst ❑ Pulse ❑ Blood pressure ❑ Eyes ❑ Mucosa Do a general physical exam: ❑ Skin (Flushing, rashes or dermatographism) ❑ Oral cavity (ulcers) ❑ CVS (Murmur) ❑ RS (Wheeze) ❑ Thyroid (Mass) ❑ Abdomen (Ascites, hepatomegaly, mass or tenderness) ❑ Anorectal (Abscess, blood, fistula or sphincter competence) ❑ Extremities (Edema)

Order routine laboratory tests ❑ CBC and differential ❑ ESR ❑ Serum electrolytes ❑ Total serum protein and albumin ❑ Thyroid function tests ❑ Urinalysis

Any specific obvious diagnosis through history and examination?

Yes

No

❑ Chronic infection (outbreaks or endemic areas): Trial of oral metronidazole 500 mg TID for 5 days for protozoal diarrhea OR oral ciprofloxacin 500 mg BD X 3 days for enteric bacterial diarrhea ❑ Medications: Discontinuation of the drug ❑ Irritable bowel syndrome (chronic abdominal pain and altered bowel habits in the absence of any organic disorder): Trial of antispasmodic agents (oral dicyclomine 20 mg QID) OR TCA's(amitriptyline 10-25 mg OD) OR SSRI (fluoxetine 20-40 mg OD) OR rifaximin

No resolution of the diarrhea

Perform stool analysis ❑ Stool weight ❑ Stool electrolytes and fecal osmotic gap ❑ Stool pH ❑ Fecal occult blood testing ❑ Stool WBC's ❑ Stool fat: Quantitative / Sudan stain ❑ Laxative screen

This management is as per the American Gastroenterological Association guidelines for the evaluation and management of chronic diarrhea.

Detailed Management

Categorize diarrhea according to the results of the stool analysis

Stool osmotic gap > 50 mOsm/kg

Stool osmotic gap < 50 mOsm/kg

Fecal occult blood (+), WBC (+), lactoferrin (+), calprotectin(+)

Fecal fat (+)

Chronic osmotic diarrhea

Chronic secretory diarrhea, OR Motility diarrhea

Chronic inflammatory diarrhea

Chronic fatty diarrhea

Low pH: Evaluate for carbohydrate malabsorption

High Mg: Evaluate for inadvertent ingestion of magnesium or antacids and surreptitious laxative abuse.

1. Exclude infection by any/combination of the following tests ❑ Stool culture ❑ Stool for ova and parasites ❑ Stool antigen test for Giardia ❑ Bacterial overgrowth: Small bowel aspirate or breath H2 test

1. Exclude structural disease by any/combination of the following tests ❑ Small bowel radiographs ❑ Sigmoidoscopy or colonoscopy with biopsy ❑ CT abdomen ❑ UGI scopy and small bowel biopsy

1. Exclude structural disease by any/combination of the following tests ❑ Small bowel radiographs ❑ CT abdomen ❑ Small bowel biopsy and aspirate for quantitative culture

Take a careful dietary history and confirm by breath H2 test (lactose) or lactase assay in biopsy

Stool alkanization test or chromatographic and chemical tests

2. Exclude structural disease by any/combination of the following tests ❑ Small bowel radiographs ❑ Sigmoidoscopy or colonoscopy with biopsy ❑ CT abdomen ❑ Biopsy of the proximal small bowel mucosa

2. Exclude infection by any/combination of the following tests ❑ Stool culture: Standard Aeromonas, Plesiomonas, Tuberculosis etc ❑ Stool for ova and parasites ❑ Clostridium toxin assay ❑ Other specific test (Serology, ELISA, immunofluorescence to rule out virus and parasites)

2. Exclude exocrine pancreatic insufficieny by any/combination of the following tests ❑ Secretin test ❑ Stool chymotrypsin activity ❑ Bentiromide test ❑ Others (D-xylose absorption tests / Schilling test)

3. Selective testing ❑ Cholestyramine test for bile acid diarrhea ❑ Plasma peptides (Gastrin, calcitonin, vasoactive intestinal polypeptide or somatostatin) ❑ urine (5-hydroxyindole acetic acid, metanephrine or histamine) ❑ Others (TSH, ACTH stimulation test, serum protein electrophoresis or serum immunoglobulins)

Confirmatory diagnosis

Yes

No

Significant response and recovery

Specific treatment per results and symptomatic treatment

No response

Emperical therapy ❑ Adequate hydration : Oral rehydration therapy or intravenous fluids or parental nutrition ❑ Antimicrobial therapy : Trial of oral metronidazole 500 mg TID for 5 days OR oral ciprofloxacin 500 mg BD X 3 days depending upon the prevalence of bacterial or protozoal infection in a specific community or situation ❑ Bile acid binding resins: cholestyramine ❑ Opiates or octreotide

Do's

• In chronic diarrhea, always first assess volume status and adequate intravascular volume and correcting fluid and electrolyte disturbances take priority over identifying the causative agent.
• Check for the presence of warning signs before starting symptomatic therapy.
• Report to the public health authorities in case of suspected outbreaks.
• At least one fecal culture should be performed in the evaluation of immunocompetent patients with chronic diarrhea, suspecting the common pathogens, Aeromonas or Pleisiomonas though they are rare cause of chronic diarrhea in immunocompetent patients than immunocompromised patients.
• Always do a 48- or 72-hour quantitative stool collection in the work-up of chronic diarrhea except in unavoidable circumstances where you can go for spot stool analysis.
• The osmotic gap is calculated from electrolyte concentrations in stool water by the following formula : 290 - 2([Na+] + [K+]) and the osmolality of stool within the distal intestine should be used for this calculation rather than the osmolality measured in fecal fluid, because measured fecal osmolality begins to increase in the collection container almost immediately when carbohydrates are converted by bacterial fermentation to osmotically active organic acids.
• Analysis for laxatives should be done early in the evaluation of diarrhea of unknown etiology or with patient history suggestive of laxative abuse.
• An endoscope that allows specimens to be obtained from the proximal and distal duodenum and/or proximal jejunum should be the best investigation of choice in presence of steatorrhea indicating small intestinal malabsorptive disorder as the most likely etiology.
• Radiographic studies of the stomach and colon should be complementary to endoscopy and colonoscopy because barium-contrast radiograms can better detect fistulas and strictures.
• Empirical therapy is used as an initial treatment before diagnostic testing or after diagnostic testing has failed to confirm a diagnosis or when there is no specific treatment or when specific treatment fails to effect a cure.

Don'ts

• Don't treat patients with severe diarrheal dehydration using 5% dextrose with 1/4 normal saline, as using solutions with lower amounts of sodium (such as 38.5 mmol/L in 1/4 saline with 5% dextrose ) would lead to sudden and severe hyponatremia with a high risk of death.
• Oral rehydration therapy is contraindicated in the initial management of severe dehydration, in patients with frequent and persistent vomiting (more than four episodes per hour), and painful oral conditions such as moderate to severe thrush.
• Avoid opium or morphine in most cases of diarrhea because of its abuse potential, except for high-volume secretory states that responds to a sufficiently high doses of these drugs.
• Loperamide should be avoided in patients with significant abdominal pain, fever and bloody diarrhea that suggests inflammatory diarrhea.
• Dont't do any diagnostic tests that would disturb the normal eating pattern, aggravate diarrhea, diminish diarrhea, add foreign material to the gut, or risk an episode of incontinence during a 48- or 72-hour quantitative stool collection.
• All but essential medications should be avoided, and any antidiarrheal medication begun before the 48- or 72-hour quantitative stool collection period should be held.

References

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