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Diarrhea . . . . A Messy Subject

Diarrhea . . . . A Messy Subject. Mechanisms of diarrhea. Secretion Osmotic drag Malabsorption Inflammation Motility.

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Diarrhea . . . . A Messy Subject

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  1. Diarrhea . . . .A Messy Subject

  2. Mechanisms of diarrhea • Secretion • Osmotic drag • Malabsorption • Inflammation • Motility

  3. A Mongolian physician had acute onset of vomiting, abdominal cramps, and watery diarrhea while visiting the United States. His symptoms woke him from sleep at midnight and have continued into the early morning hours.

  4. He has been retching repeatedly, without emesis. His stool looks like cloudy yellow water. He does not have fever or rectal bleeding. • On exam his pulse is 100, rising to 114 when he sits up. T 36.4 Abdomen is soft, nondistended, nontender. • What is your diagnosis?

  5. The following morning he feels weak, but his vomiting and diarrhea have stopped. He learns that 3 others who he dined with yesterday were sick also.

  6. Food Poisoning • Pre-formed toxin: symptoms in 4 - 8 hours • nausea, vomiting, secretory diarrhea • illness lasts 24 hours • Ingested pathogen: symptoms in 2 - 3 days

  7. Secretion • Symptom: profuse watery stool • Mechanism: active secretion of fluid and electrolytes from the gut mucosa, overwhelming colonic absorption capacity • No fever, blood in the stool, or leukocytes in the stool

  8. Stool Osmotic Gap • Gut contents are iso-osmotic with serum • Serum osmolality is approx 290 mosm/l • Stool osmolar gap = 290 – (Na + K)*2 • If stool osmolar gap is < 50, diarrhea is considered secretory

  9. Secretory Diarrhea • Acute • cholera, food poisoning, clostridium dificile colitis, severe giardiasis • Chronic • neuroendocrine tumors, diabetes, collagenous colitis

  10. Vibrio Cholerae • Epidemic • Toxin affects chloride and sodium pumps in the apical cell membrane of enterocytes • Small bowel secretion • Rehydration (oral or IV) • ORS: glucose vs starch • antibiotics

  11. ORS for secretory diarrhea • Stimulates glucose/sodium co-transporter • ORS must contain carbohydrates • Promotes fluid absorption in small bowel • Should be iso-osmotic • Complex starches (rice) rather than glucose • more carbohydrate delivery • increased efficacy

  12. Oral rehydration saves lives WGO Practice Guideline – Acute Diarrhea March 2008

  13. Oral rehydration solution (ORS) Rice-based ORS is superior to glucose-based ORS in patients with cholera WGO Practice Guideline – Acute Diarrhea March 2008

  14. A 28 year old mother complains of diarrhea. For the past several months she has had 6 loose watery mushy stools a day. She has not seen blood or grease in the stool. Since developing diarrhea she has lost 20 pounds despite a good appetite. No fever or abdominal pain. She says that food goes right through her, and her diarrhea slows if she skips a meal.

  15. Pulse 80, not postural. T 36. Pale conjunctiva. Mildly enlarged cervical and inguinal nodes. Chest and cardiac exams normal. Abdomen soft, nontender, no organomegaly. • Stool mushy, yellow, foul smelling, negative for occult blood.

  16. Hemoglobin = 8.2 gr/dl • HIV test: positive • Stool for ova and parasites: negative • What is your diagnosis?

  17. Ameoba, Giardia • Cryptosporidium • Microsporidium • Mycobacterial infections • CMV • AIDS enteropathy

  18. Symptoms persist despite a course of metronidazole • Stool acid fast stain shows cryptosporidium

  19. Malabsorption • Symptom: diarrhea after eating, weight loss, flatulence, steatorrhea • Signs of nutrient deficiency (anemia) • Mechanism: unabsorbed nutrients are metabolized by colonic bacteria producing gas, osmotically active molecules • Diagnosis: fecal fat

  20. Sudan Stain

  21. Malabsorption • Pancreatic insufficiency • Visible oil in the stool • Small bowel mucosal disease • No visible oil in the stool • Celiac sprue • Chronic small bowel infections: tropical sprue, giardia • AIDS small bowel pathogens

  22. Sprue

  23. Sprue • Tropical sprue • 30 to -30 degrees latitude • Folate, B12 malabsorption • Folic acid, tetracycline • Celiac disease • Iron, calcium malabsorption • Serum antigliadin and tissue transglutaminase antibodies • HIV enteropathy • HAART

  24. Giardia Lamblia • Small bowel pathogen • secretion/malabsorption • metronidazole resistance: • higher dose metronidazole, albendazole, tinidazole • furazolidone, quinacrine • paromomycin (preganancy)

  25. Cryptosporidium • Parasitic infection of small bowel enterocytes • Little or no inflammatory reaction • Chronic illness in AIDS, malnourished children • Paromomycin

  26. Mycobacterium Avium

  27. A 4 year old girl is admitted to the hospital with failure to thrive. She and all her siblings developed diarrhea six weeks ago. Her siblings all recovered after a few days, but she continued to have frequent loose stools. She has become inactive and irritable.

  28. T 36, pulse 80, not postural. Weight down 2 kg compared to previous visit. Pale conjunctiva. No adenopathy. Chest clear. Abdomen soft, normal bowel sounds, not distended or tender. No organomegaly. Mild pitting edema. • Stool brown, pasty, negative for occult blood or leukocytes

  29. Hgb = 9.2 • malaria smear: negative • HIV test: negative • Stool for ova and parasites: negative • What is your diagnosis?

  30. Post-infectious diarrhea • Up to 8% of acute diarrheal illnesses become chronic in children • Mucosal atrophy (small bowel and colon), malabsorption, failure to thrive, death • Enteropathogenic e coli, giardia, cryptosporidium

  31. Nutritional Rx for chronic diarrhea in children • Nutritional support • Amylase-resistant starch (pectin, green banana) • Iso-osmotic, incompletely metabolized in small bowel • Metabolized to short chain fatty acids in colon (preferred nutrient for colonic mucosa) • Antibiotics (PCN or neomycin), folic acid • Zinc and MVI

  32. A 6 year old boy is brought to the emergency department by his family because of weakness and confusion. He has had diarrhea for the past 3 days. He has frequent small stools which are bloody, and complains of abdominal pain. He has been eating well, no vomiting.

  33. Pulse 110, not postural. T 38.5, respiratory rate 22. Irritable, lethargic. Neck supple. Chest clear, cardiac exam normal. Abdomen soft, flat, not tympanitic, normal bowel sounds, tender in right and left lower quadrants, no guarding or rebound. • Small amount of bloody stool in his clothes. • What is your diagnosis?

  34. Hgb: 13 g/dl • WBC: 24,000 cells/mm3 • KUB: normal • Malaria smear: negative • LP: no cells, low protein • Fecal leukocytes: positive • Stool for ova and parasites: negative

  35. Should he receive antibiotics? • If so, which one?

  36. Gut inflammation • Symptoms: frequent small stools, blood, white cells in stool, abdominal pain, fever, tenesmus • Mechanism: inflamed mucosa exudes fluid, electrolytes, proteins; increased colonic motility

  37. Inflammation • Colitis • Infectious (Dysentery) • Ischemic • drug-induced (ampicillin, NSAIDS) • Inflammatory (ulcerative colitis, Crohn’s disease) • Small bowel inflammation

  38. Diffuse colitis • Bacterial pathogens • Ulcerative colitis • Drugs (ampicillin)

  39. Segmental colitis • Enterohemorrhagic e coli • Ischemia • Crohn’s disease • NSAID induced

  40. CMV colitis

  41. Entameba Histolytica • Colonic infection: colitis, asymptomatic cyst passage • Extraintestinal infection • metronidazole followed by diloxanide or iodoquinol • IV metronidazole for severe colitis or liver abscess

  42. Bacterial Enterocolitis • Self-limited illness (e coli, shigella, etc) • Antibiotics for severe disease (fever and bloody diarrhea), extremes of age, immunocompromised patients, suspicion of enteric fever. • Antibiotics may precipitate hemolytic-uremic syndrome (HUS) in patients with enterohemorrhagic e coli • Avoid anti-motility agents

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