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.pdfGeriatric Considerations
Fecal impaction or obstructing neoplasm can cause overflow diarrhea with chronic constipation.
DIFFERENTIALDIAGNOSIS
IBD
Malabsorption
Medications (cholinergic agents, magnesium-containing antacids, chemotherapy, antibiotics)
C. difficile colitis secondary to antibiotic use
Diverticulitis, ischemic colitis
Spastic (irritable) colon
Fecal impaction
Endocrinopathies: thyroid disease
Neoplasia
DIAGNOSTIC TESTS & INTERPRETATION
Initial Tests (lab, imaging)
Laboratory testing is reserved for patients with persistent fever, moderatesevere disease, bloody stool, immunosuppression, or symptoms lasting >7 days or in suspected outbreaks (3)[C].
CBC
–Leukocytosis, anemia (blood loss), eosinophilia (parasite infection), thrombocytopenia (hemolytic-uremic syndrome [HUS])
Serum electrolytes
BUN and creatinine may elevate with volume depletion.
Nonanion gap metabolic acidosis
Stool sample
–Occult blood (IBD, bowel ischemia, and certain bacterial infections)
–Fecal leukocytes
–Stool ova and parasites
–Stool culture: for bloody diarrhea, consider Salmonella, Shigella,
Campylobacter, E. coli 0157:H7, Y. enterocolitica, E. histolytica
–C. difficile toxin (especially IBD, recently hospitalized or recent antibiotic use) (4)[C]
–Giardia ELISA>90% sensitive in at-risk population
–Abdominal radiographs (flat plate and upright) if severe abdominal pain or concern for obstruction
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–Abdominal CTscan is preferred to evaluate intra-abdominal and intestinal disease (5)[C].
Diagnostic Procedures/Other
Consider sigmoidoscopy or colonoscopy in patients with persistent diarrhea, when there is no clear diagnosis after routine blood and stool tests, and if empiric or supportive therapy is ineffective.
Consider colonoscopy in immunocompromised patients to evaluate for CMV colitis.
Colonoscopy helps to distinguish infectious diarrhea from IBD, ischemic colitis, cancer, or other noninfectious etiologies (5)[C].
TREATMENT
GENERALMEASURES
Oral rehydration and electrolyte management are key to successful treatment.
Diet, as tolerated—“if the gut works, use it.”
Balanced electrolyte rehydration solutions recommended in elderly and profuse, watery TD (3)[C]
IV fluids if patient cannot tolerate oral rehydration or presents with severe dehydration
MEDICATION
First Line
Consider empiric antibiotics (fluoroquinolones or macrolides) in patients with signs and symptoms of systemic infection, severe disease, or clear cases of TD (3)[C].
–Fever; bloody diarrhea; fecal leukocytes
–Immunocompromised host
–Signs of severe volume depletion
–Symptoms >1 week
Tailor antibiotics to stool culture results (3)[C].
–Giardia: metronidazole 250 mg PO TID for 5 to 7 days, tinidazole 2 g PO once
–E. histolytica: metronidazole 500 to 750 mg PO TID for 7 to 10 days, tinidazole 2 g PO daily for 3 to 5 days
–Shigella: ciprofloxacin 500 mg PO BID for 3 to 5 days or ceftriaxone 1 to 2
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g IM/IVdaily for 5 days
–Campylobacter: azithromycin 500 mg PO daily for 3 to 5 days or erythromycin 500 mg PO QID for 5 days
–C. difficile: metronidazole 250 to 500 mg PO/IV every 6 to 8 hours for 10 to 14 days, vancomycin 125 to 500 mg PO QID for 10 to 14 days, or fidaxomicin 200 mg PO BID for 10 days; consider fecal microbiota transplant in recurrent mild to moderate C. difficile infections.
–TD: ciprofloxacin 500 mg PO BID for 1 to 3 days, azithromycin 500 mg PO daily for 1 to 3 days, rifaximin 200 mg PO TID for 3 days; combined with loperamide 4 mg PO initial dose, followed by 2 mg after each episode of diarrhea for maximum of 8 mg daily; loperamide or BSS may be used alone in cases of mild TD (2)[C].
General considerations
–Antibiotics are not recommended in Salmonella infections unless caused by Salmonella typhosa or if the patient is febrile or immunocompromised.
–Avoid antibiotics in patients with E. coli 0157:H7 due to risk for HUS.
–Antibiotics are not indicated for foodborne toxigenic diarrhea.
–Avoid antimotility agents (e.g., loperamide) in patients with febrile or bloody diarrhea (especially, E. coli 0157:H7) or antibiotic-associated colitis.
–Antimotility agents used in combination with antibiotics may speed recovery from TD.
–Antibiotics are not recommended for the treatment of mild TD (2)[C].
–C. difficile infections in IBD patients: Initially treat with vancomycin or fidaxomicin; consider fecal microbiota transplant in patients with recurrent
C. difficile infections (4)[C].
Significant medication interactions
–Salicylate absorption from BSS can cause toxicity in patients already taking aspirin-containing compounds and may alter anticoagulation control in patients taking warfarin.
–Avoid alcoholic beverages with metronidazole due to the possibility of a disulfiram reaction.
COMPLEMENTARY& ALTERNATIVE MEDICINE
BSS may help control rate of diarrhea stools (3,6)[C].
Probiotics are recommended for prevention of antibiotic-associated diarrhea and C. difficile infection recurrence and to treat acute infectious diarrhea in setting of symptomatic IBS (6)[C].
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Probiotic use above 1010/g may help in patients with antibiotic-associated diarrhea (2)[A].
Probiotic strains Lactobacillus rhamnosus GG (LGG) and Saccharomyces boulardii most effective; may reduce duration by up to 1 day
Probiotics should be avoided in immunocompromised patients (2)[A].
Zinc supplementation can decrease diarrhea duration as well as associated morbidity and mortality.
ADMISSION, INPATIENT, AND NURSING CONSIDERATIONS
Outpatient management, except for patients who are severely ill with signs of volume depletion
ONGOING CARE
DIET
Early refeeding is encouraged. Regular diets are as effective as restricted diets.
The traditional bananas, rice, applesauce, toast (BRAT) diet has little evidence-based support, despite heavy clinical use, and may result in suboptimal nutrition.
During periods of active diarrhea, coffee, alcohol, dairy products, fruits, vegetables, red meats, and heavily seasoned foods may exacerbate symptoms.
PATIENT EDUCATION
See guidelines in “General Prevention” section.
PROGNOSIS
Acute diarrhea is rarely life-threatening if adequate hydration is maintained.
COMPLICATIONS
Volume depletion, shock, sepsis
Anemia
Hemolytic uremic syndrome with E. coli 0157:H7
Guillain-Barré syndrome with C. jejuni
Reactive arthritis with Salmonella, Shigella, and Yersinia
Functional bowel disorders (e.g., postinfectious irritable bowel syndrome [PI-
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IBS])
REFERENCES
1.Barr W, Smith A. Acute diarrhea. Am Fam Physician. 2014;89(3):180–189.
2.Riddle MS, Connor BA, Beeching NJ, et al. Guidelines for the prevention and treatment of travelers’diarrhea: a graded expert panel report. J Travel Med. 2017;24(Suppl 1):S57–S74.
3.Riddle MS, DuPont HL, Connor BA. ACG clinical guideline: diagnosis, treatment, and prevention of acute diarrheal infections in adults. Am J Gastroenterol. 2016;111(5):602–622.
4.Khanna S, Shin A, Kelly CP. Management of Clostridium difficile infection in inflammatory bowel disease: expert review from the Clinical Practice Updates Committee of the AGAInstitute. Clin Gastroenterol Hepatol. 2017;15(2):166–174.
5.DuPont HL. Acute infectious diarrhea in immunocompetent adults. N Engl J Med. 2014;370(16):1532–1540.
6.Wilkins T, Sequoia J. Probiotics for gastrointestinal conditions: Asummary of the evidence. Am Fam Physician. 2017;96(3):170–178.
ADDITIONALREADING
Chapman BC, Moore HB, Overbey DM, et al. Fecal microbiota transplant in patients with Clostridium difficile infection: a systematic review. J Trauma Acute Care Surg. 2016;81(4)756–764.
Islam S. Clinical uses of probiotics. Medicine (Baltimore). 2016;95(5):e2658.
Santos VS, Marques DP, Martins-Filho PR, et al. Effectiveness of rotavirus vaccines against rotavirus infection and hospitalization in Latin America: systematic review and meta-analysis. Infect Dis Poverty. 2016;5(1):83.
World Health Organization. The top 10 causes of death in the world, 2000 and 2012 fact sheet. http://www.who.int/mediacentre/factsheets/fs310/en/. Accessed January 13, 2017.
SEE ALSO
Botulism; Cholera; Food Poisoning, Bacterial
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CODES
ICD10
R19.7 Diarrhea, unspecified
A09 Infectious gastroenteritis and colitis, unspecified
A08.4 Viral intestinal infection, unspecified
CLINICALPEARLS
Viruses are the most common causes of acute diarrheal illness in the United States.
Oral rehydration is the most important step in treating acute diarrhea.
Routine stool culture is not recommended, unless patients present with bloody diarrhea, fever, severe dehydration, signs of inflammatory disease, persistent symptoms >7 days, or immunosuppression.
Start empiric antibiotics in patients who are severely ill or immunocompromised.
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DIARRHEA, CHRONIC
Stephen M. Testa, MD 
Marie L. Borum, MD, EdD, MPH
BASICS
DESCRIPTION
An increase in frequency of defecation, urgency, or decrease in stool consistency (typically >3 loose stools per day) for >4 weeks (1,2)
–Abnormal form is the most important defining factor; frequent defecation with normal consistency is termed pseudo-diarrhea (2).
Etiologies include osmotic, secretory, malabsorptive, inflammatory, infectious, and hypermotility.
Infectious causes of chronic diarrhea are uncommon in immunocompetent patients. Parasitic etiologies are more common than bacterial.
EPIDEMIOLOGY
Prevalence
Varies by etiology, overall ~3–5% of the population in developed countries is affected (2).
ETIOLOGYAND PATHOPHYSIOLOGY
Chronic diarrhea is typically the result of disturbances in intestinal luminal water and electrolyte balance.
Osmotic (fecal osmotic gap >75 mOsm/kg) (2)
–Carbohydrate malabsorption
Disaccharides including lactose
Monosaccharides including fructose
Polyols including sorbitol, xylitol, sucralose, and saccharin (common sugar substitutes)— cannot be metabolized and create an osmotic gradient
–Magnesium, phosphate, and sulfate overload
Secretory (fecal osmotic gap <50 mOsm/kg) (2)
–Stimulant laxative ingestion
–Postcholecystectomy
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Excessive intestinal bile salts cause choleretic diarrhea; often resolves in
6 to 12 months
–Ileal bile acid malabsorption
–Ileal resection of <100 cm leads to choleretic diarrhea due to excessive colonic bile salts.
–Disordered motility 
Postvagotomy
Diabetic autonomic neuropathy
Hyperthyroidism
–Neuroendocrine tumors 
VIPoma
Gastrinoma
Somatostatinoma
Carcinoid syndrome
–Metastatic medullary carcinoma of the thyroid
–Systemic mastocytosis
–Protein-losing enteropathy
Malabsorption (2)
–Celiac disease
–Whipple disease
–Giardiasis
–Short bowel syndrome
Ileal resection of >100 cm leads to insufficient bile salt concentrations in the duodenum for optimal fat absorption, leading to fat and fat-soluble vitamin malabsorption.
–Small intestinal bacterial overgrowth
–Pancreatic exocrine insufficiency (cystic fibrosis [CF], chronic pancreatitis)
–Inadequate bile acid production/secretion
Inflammatory (2)
–Ulcerative colitis
–Crohn disease
–Microscopic colitis (lymphocytic or collagenous)
–Vasculitis
–Radiation enterocolitis
–Eosinophilic enterocolitis
Hypermotility (normal fecal osmotic gap) (1,2)
–Irritable bowel syndrome (IBS)
–Functional diarrhea
Drugs (2)
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–Adverse effect of >700 drugs, most commonly: NSAIDs, PPIs, colchicine, metformin, digoxin, SSRIs
–Factitious diarrhea: excessive laxative use
Herbal products: St. John’s wort, echinacea, garlic, saw palmetto, ginseng, cranberry extract, aloe vera
Infectious (2)
–Bacterial: Clostridium difficile, Mycobacterium avium intracellulare
–Viral: cytomegalovirus
–Parasitic: Giardia lamblia, Cryptosporidium, Isospora, Entamoeba histolytica
–Helminthic: Strongyloides
Food allergies (2)
Genetics
Celiac disease is associated with HLA-DQ2 and HLA-DQ8 haplotypes on major histocompatibility complex (MHC) class II antigen-presenting cells (3).
IBD is polygenic (4).
CF is caused by a mutation in the CF transmembrane conductance regulator (CFTR), resulting in abnormal exocrine gland secretions.
RISK FACTORS
Osmotic
–Excessive ingestion of nonabsorbable carbohydrates
–Lactose intolerance
–Celiac disease
Secretory (2)
–Postsurgical: extensive small bowel resection/ileal surgery, vagotomy, bile acid malabsorption
–History of neuroendocrine disease
–History of stimulant laxative abuse
–Dysmotility syndromes
Malabsorptive
–CF
–Chronic alcohol abuse
–Chronic pancreatitis/pancreatic insufficiency
–Celiac disease
–Medications (e.g., orlistat, acarbose)
Inflammatory
– Inflammatory bowel disease (IBD)
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–NSAID use
–Thoracoabdominal radiation
–HIV/AIDS
–Antibiotic use
–Immunosuppressant therapy
Hypermotility
–Psychosocial stress
–Preceding infection
Genetic predisposition
ALERT
Diabetes mellitus and/or prior cholecystectomy both cause secretory and osmotic diarrhea.
GENERALPREVENTION
Varies by etiology; treat the underlying cause.
COMMONLYASSOCIATED CONDITIONS
Extraintestinal manifestations of IBD include arthralgias, aphthous stomatitis, uveitis/episcleritis, erythema nodosum, pyoderma gangrenosum, perianal fistulas, rectal fissures, ankylosing spondylitis, and primary sclerosing cholangitis.
Celiac disease is associated with dermatitis herpetiformis, type 1 diabetes, other autoimmune disorders and IgAdeficiency.
Many patients with IBS have behavioral comorbidities.
Latex-food allergy syndrome: associated allergies to latex and banana, avocado, kiwi, and walnut (2)
DIAGNOSIS
HISTORY
Detailed history of symptoms (1,2):
–Onset, pattern, and frequency
–Stool volume and quality (including presence of blood or mucus)
–Presence of nocturnal symptoms
–Travel history
–Antibiotic exposure
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