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

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

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

Adults with chronic diarrhea (> 4 weeks)

History ❑ Onset : Congenital / abrupt / gradual ❑ Pattern : Continuous / intermittent ❑ Duration ❑ Epidemiology : Travel / food / water ❑ Stool characteristics : Watery / bloody / fatty ❑ Abdominal pain ❑ Weight loss ❑ Fecal incontinence ❑ Aggravating factors : Diet / stress ❑ Mitigating factors : Diet / over-the-counter drugs / use of prescription ❑ Previous evaluations ❑ Iatrogenic : Medication / radiation therapy / surgery ❑ Factitious diarrhea : Eating disorders / laxative ingestion / malingering ❑ Systemic disease : Cancer, diabetes, HIV, hyperthyroidism, other conditions

Physical Examination ❑ General : Nutrition / vitals / volume status ❑ Skin : Flushing / rashes / dermatographism ❑ CVS : Murmur ❑ RS : Wheeze ❑ Thyroid : Mass ❑ Abdomen : Ascitis / hepatomegaly / mass / tenderness ❑ Anorectal : Abscess / blood / fistula / sphincter competence ❑ Extremities : Edema

Routine laboratory tests ❑ CBC and differential : Anemia / eosinophilia / leucocytosis ❑ ESR ❑ Serum electrolytes ❑ Total serum protein and albumin ❑ Thyroid function tests

Stool analysis ❑ Weight ❑ Stool electrolytes / fecal osmotic gap ❑ Stool pH ❑ Fecal occult blood testing ❑ Stool WBC's : Inflammation ❑ Fat output : Quantitative / Sudan stain ❑ Laxative screen

Categorize diarrhea

Chronic osmotic diarrhea

Chronic secretory diarrhea

Chronic inflammatory diarrhea

Chronic fatty diarrhea

Low pH : Carbohydrate malabsorption

High Mg : Inadvertent ingestion or laxative abuse.

Exclude infection ❑ Stool culture ❑ Stool for ova and parasites ❑ Giardia antigen ❑ Bacterial overgrowth : Small bowel aspirate or breath H2 test

Exclude structural disease ❑ Small bowel radiographs ❑ Sigmoidoscopy or colonoscopy with biopsy ❑ CT abdomen ❑ Small bowel biopsy

Exclude structural disease ❑ Small bowel radiographs ❑ CT abdomen ❑ Small bowel biopsy and aspirate for quantitative culture

Dietary review / breath H2 test (lactose) or lactase assay in biopsy

Exclude structural disease ❑ Small bowel radiographs ❑ Sigmoidoscopy or colonoscopy with biopsy ❑ CT abdomen ❑ Biopsy of the proximal small bowel mucosa

Exclude infection ❑ Stool culture : Standard Aeromonas, Plesiomonas, tuberculosis ❑ Clostridium toxin assay ❑ Other specific test : Virus and parasites

Exclude exocrine pancreatic insufficieny ❑ Secretin test ❑ Stool chymotrypsin activity ❑ Bentiromide test ❑ Others : D-xylose absorption tests / Schilling test

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

No confirmatory diagnosis / no specific treatment

Emperical therapy ❑ Adequate hydration : ORS / IVF / parental nutrition ❑ Antimicrobial therapy : Depending upon the prevalence of bacterial or protozoal infection in a specific community or situation ❑ Bile acid binding resins : cholestyramine ❑ Opiates / octreotide

References

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