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Acute and Chronic Diarrhea

Acute and Chronic Diarrhea. Outline. Definitions/Epidemiology Mechanisms of Diarrhea Tools for evaluation Approach to acute diarrhea Approach to chronic diarrhea. Disclaimer. Focus on diarrheal illnesses in developed countries Topics not specifically or adequately discussed:

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Acute and Chronic Diarrhea

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  1. Acute and Chronic Diarrhea

  2. Outline • Definitions/Epidemiology • Mechanisms of Diarrhea • Tools for evaluation • Approach to acute diarrhea • Approach to chronic diarrhea

  3. Disclaimer • Focus on diarrheal illnesses in developed countries • Topics not specifically or adequately discussed: • Outbreak/disaster medicine • Immunocompromised hosts (see GI illness in HIV/AIDS) • pediatrics

  4. Clinical Challenges • Diarrhea is a common presenting complaint • FoodNet survey – 0.72 episodes per person-years • CDC estimates: • 135 million/yr Non-foodborne gastroenteritis • 76 million/yr foodborne gastroenteritis

  5. Definitions • Acute diarrhea • > 200 grams / day VS • 3 or more loose stools / day • Termed persistent if lasting > 14 days • Chronic diarrhea • > 1 month

  6. Mechanisms of diarrhea • Intestines lack concentrating ability • Osmolality of the gut maintained at 290 • In a normal 10 liter day => jejunum absorbs 6 L, ileum 2.5 L, and colon 1.4 L • 99% absorbed

  7. Mechanisms of Diarrhea • Net balance of too little sodium absorption OR too much chloride/bicarb secretion • Variety of intracellular targets to drive the above (see cholera toxin) • Consider motility another variable in the equation • Paracrine/Immune/Neural/Endocrine influence

  8. Mechanisms of Diarrhea • Infectious diarrhea • Toxingenic • Alter Na/water transport W/O affecting mucosal morphology • Cytotoxic • Induces acute inflammation and secretion • Invasive • Penetration of organism (normally an enterotoxin is produced as well) • Enteroadherent • Only the cell cytoskeleton is altered

  9. Tools for evaluation • Tests for inflammation • Fecal white blood cells – sensitivity of 70% and specificity of 50% • Stool lactoferrin – latex agglutination test for protein produced by PMNs – sensitivity/specificity 90/100. • Tests for toxins • Shiga toxin • C. diff toxin A/B

  10. Tools for evaluation • Tests to isolate the pathogen • Stool culture • Routine testing performed for shigella, salmonella, and campylobacter • Make special mention for: • E coli O157:H7 • Yersinia • Vibrio • Aeromonas / Plesiomonas

  11. Tools for evaluation • Tests to isolate the pathogen 2. Stool ELISA • Giardia • E. histolytic 3. Stool Ova and Parasites • Tests to obtain tissue for histopathology • EGD – cryptosporidia, microsporidia, isospora belli, and MAI • Flexible Sigmoidoscopy – pseudo membranous colitis and CMV • Colonoscopy - TB

  12. Clinical Vignette 46 y/o female with h/o DMII, HTN, HLP presents with 1.5 days of moderate lower abdominal cramping, nausea, vomiting, and non-bloody diarrhea (5/day). Low grade fevers noted at home and she denied sick contacts, recent travel, or recent antibiotics. PMHx: HTN, HLP, DMII PSHx: C/S, thyroid cyst removed Meds: lantus, zocor, ASA, lisinopril, ALL: NKDA Famhx: CAD, DMII SocHx: married, lives in El Cajon, works in a bank

  13. Clinical Vignette PE: 99.8, 102, 105/56, 18 98% on RA, 6/10 pain Gen: ill appearing female Heent: anicteric Lungs: CTA B CV: RRR Abd: slightly obese, TTP right periumbilicus and right lower quad. (by report ? of rebound guarding) Ext: no LE edema Rectal: minimal stool, not bloody

  14. Clinical Vignette Labs:

  15. Approach to Acute Diarrhea • Important Issues: • How sick is your patient? • Dehydration (number of stools / day) • Signs of inflammation – fever • Abdominal pain (invasive organism) • Bloody diarrhea (invasive organism) • How sick can your patient become? • Immunocompromised patient • Elderly patient • Hospitalized patient/recent abx • Pregnant patient

  16. Approach to Acute Diarrhea • General rules of thumb • Vast majority of diarrheal illnesses are self-limiting • We are poor at identifying causative organisms • Rate of positive culture 1.5-5.6% • When you select “severe” cases the rate can increase to 87% (bacterial) • Treatment makes us feel better but for most cases there is no or little evidence it helps and some concern that it could make things worse • Treatment typically reserved for inflammatory diarrheas

  17. Approach to Acute Diarrhea

  18. Approach to Acute Diarrhea • Indications for Antimicrobial therapy • Bacterial infection • Shigella • Vibrio cholerae • Clostridium difficile • Traveler’s diarrhea • Salmonellosis (extraintestinal) • Salmonellosis (with toxicity) • Campylobacter diarrhea (prolonged) • Protozoal infection • Giardia lamblia • Entamoeba histolytica • STD • Gonorrhea • Syphilis • Chlamydia • HSV

  19. Chronic Diarrhea • Classification more helpful • Osmotic • Inflammatory • Fatty • Secretory

  20. Tools for Evaluation • History • Useful to find the “functional phenotype” • Symptoms > 1 yr; lack of wt loss; straining to have BM; lack of nocturnal diarrhea • Stool spot testing • Occult blood – 50% of patients with celiac will be positive • Fecal WBC – usually not helpful • Sudan stain for fat – qualitative measure that is user dependent and variable ability to “quantify” fecal fat; some use as a “screening test” • Culture – mainly for aeromonas/pleisiomonas (esp. if well water/fresh ponds and streams); candida albicans • O&P – rarely used and favor stool ELISA for giardia/h histolytica (will need special tools to identify crypto/microsporidia)

  21. Tools for Evaluation • Quantitative testing (48-72 hour collection) • Weight • Fat content • Osmolality • Electrolyte concentration • Magnesium • Fecal chymotrypsin/elastase • Laxative testing

  22. Tools for Evaluation • Stool weight • If > 500 g/d unlikely IBS • If > 1000 g/d likely pancreatic • Osmolar gap (290 -2(Na+K)) • If >125 mOsm/kg think osmotic diarrhea • If <50 mOsm/kg think pure secretory • If 50-125 still consider modest carbohydrate malabsorption

  23. Tools for Evaluation • Stool pH • If pH <5.3 then think carbohydrate malabsorption (especially lactulose/sorbitol) • Stool osm • If low then contamination with dilute urine or gastrocolic fistula with hypotonic fluid

  24. Tools for Evaluation • Stool fat output • Normal 7 grams/day (9% of intake) • Can achieve 7-14 grams/day during episode of diarrhea (“secondary steatorrhea”) • If >14 g/d then think exocrine pancreas, small intestine, and bile salts • Fat concentration • If < 9.5 g/100 g stool – small bowel disease • If > 9.5 g/100 g stool – exocrine pancreas or bile salt issue

  25. Tools for Evaluation • Jejunal aspirate • SIBO – “defined” at > 106 organisms/mL • Short bowel patients • Diabetics • Scleroderma • Stricturing disease (Crohn’s dz, radiation, surgery) • Pancreatic insufficiency • Fecal elastase (ELISA) • Bentiromide – reagent requires chymotrypsin for cleavage

  26. References • Fine KD, Schiller LR et al. AGA Technical Review on the Evaluation and Management of Chronic Diarrhea. Gastroenterology 1999;116(6):1464-1486. • Guerrant R, Pawlowski SW, Warren CA. Diagnosis and Treatment of Acute or Persistent Diarrhea. Gastroenterology 2009;136:1874=1886. • Holtz LR, Neill MA, Tarr PI. Acute Bloody Diarrhea: A Medical Emergency for Patients of All Ages. Gastroenterology 2009;136:1887=1898. • Schiller LR. Diarrhea and Malabsorption in the Elderly. Gastroenterol Clin N Am 2009;38:481-502. • Sleisenger and Fordtran’s Gastrointestinal and Liver Disease. 8th ed. Saunders, 2006.

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