Acute and Chronic Diarrhea

1. Acute and Chronic Diarrhea Dr.Atakan YeşilYeditepe University Department of Gastroenterology

2. Intestinal Fluid Movement (water follows solutes)

3. DIARRHEA • Familiar to all of us • Increased stool volume • Usually to >> 200 ml/24 hours • Altered stool consistency • Increased liquidity • Increased number of stools (not always)

4. Diarrhea occurs when SB/colon solute loads exceed their absorptive capacities. Small bowel Colon NORMAL DIARRHEA

5. DIARRHEA - Mechanisms • Too much input • Not enough absorption • Combination of both

6. Chronic Diarrhea • Chronic diarrhea should be defined as a decrease in fecal consistency lasting for four or more weeks

7. A myriad of disorders are associated with chronic diarrhea

9. The prevalence of specific disorders varies based upon the practice setting. • In developed countries, common causes are irritable bowel syndrome (IBS), inflammatory bowel disease, malabsorption syndromes (such as lactose intolerance and celiac disease), and chronic infections (particularly in patients who are immunocompromised).

10. Optimal strategies for the evaluation of patients with chronic diarrhea have not been established. • The selection of specific tests, timing of referral, and the extent to which testing should be performed depend upon an appraisal of the likelihood of a specific diagnosis, the availability of treatment, the severity of symptoms, patient preference, and comorbidities.

12. A thorough medical history can guide appropriate evaluation

14. Mechanisms of Diarrhea • Secretory Diarrhea • Osmotic diarrhea/malabsorption • Increased bowel motility • Decreased bowel surface area • Inflammation

15. Secretory Diarrhea - A problem of excess input of electrolytes (NaCl) with water following.

16. Clinical Manifestations of Secretory Diarrhea • Large volume, watery diarrhea • Little response to fasting • Stool compositon is similar to plasma • (high NaCl) • Dehydration and plasma electrolyte imbalance are common • No WBC or RBC in stool

17. Consequences of Large Volume Diarrhea/Secretory Diarrhea • Dehydration due to massive loss of fluid overwhelming homeostatic mechanisms • Electrolyte abnormalities • Hypokalemia (loss of K in stools) • Acidosis (loss of bicarbonate in stools) • Hyponatremia (loss of Na in stools and oral intake of free water)

18. Origin of Electrolyte Abnormalities • Dehydration: loss of 1-7 liters per day of liquid containing 80-100 mEq/liter Na • Hyponatremia: loss of sodium and replacement orally with hypotonic fluids (water, sodas, fruit juices) in the presence of ADH (anti-diuretic hormone) • Hypokalemia: stool K is high – may reach 40-80 mEq/liter. 2 liters of stool with 45 mEq/liter K in it is a daily loss of 90 mEq which is difficult to replace. (1 medium banana has 19 mEq)

19. Causes of Intestinal Secretion – Istimulation of NaCl secreation • Bacterial toxins • Cholera, E. coli, Shigella, etc. • Inflammatory mediators • prostaglandins • Circulating hormones • Gastrin (Z-E syndrome), Vasoactive intestinal polypeptide (VIP)

20. Causes of Intestinal Secretion - II • Malabsorbed compounds that reach the colon and stimulate secretion • Bile acids • Fatty acids • Laxatives (“natural” from plants) that stimulate secretion • Ricinoleic acid • Senokot • Lack of mature villus/surface absorptive cells reducing absorption • viral gastroenteritis/celiac sprue

21. Osmotic Principles • The driving force of fluid movement is ion or solute transport • Solutes may be actively transported through cell membranes • Solute may move passively through cells following concentration and/or electrical gradients • Water movement follows solute movement by osmosis • Water may move between cells (tight junctions) or through cell membrane channels (aquaporins)

22. Clinical Manifestations of Osmotic Diarrhea • Moderate volume of stool • Improves/disappears when oral intake stops • Moderately watery/soft stool • Often associated with increased flatus if due to carbohydrate malabsorption (see malabsorption lecture) • No WBC or RBC in stool

23. Examples of Osmotic Diarrhea • Ingestion of non-absorbable compounds • Magnesium salts • Antacids • Laxatives • Sugars • Lactulose, sorbitol, mannitol, fructose, lactose • Malabsorption of specific carbohydrates • Disaccharidase deficiency • Generalized malabsorption of nutrients

24. Therapeutic agents that cause osmotic diarrhea: lactulose (used medically) and magnesium salts Magnesium citrate Lactulose

25. Causes of Osmotic Diarrhea Poorly absorbed sugars such as: Sorbitol Fructose Elsie esq., Flickr

26. Sources of Sorbitol Leading to Osmotic Diarrhea Patricil, Flickr

27. Clues to Osmotic Diarrhea from Clinical Lab Tests • Fecal electrolytes • Fecal osmotic gap

30. Diarrhea Due to Increased Bowel Motility Rapid intestinal motility may result in diarrhea due to reduced contact time between luminal contents and bowel mucosa. Examples include: Anxiety Hyperthyroidism Irritable bowel syndrome Postvagotomy diarrhea (dumping syndrome) Bowel infection (viral gastroenteritis)

31. Loss of Bowel Surface Area • Functionally equivalent to increased bowel motility • Underlying process causing loss of surface area may produce additional symptoms/signs • Causes include surgical resection, mucosal disease, fistulas

32. Inflammation and Diarrhea Normal Colon Ulcerative Colitis/Shigella dysentery

33. Clinical Manifestations of Inflammatory Diarrhea • Fever and systemic signs of inflammation (if severe/invasive organism) • Small to moderate volume of diarrhea • Bloody diarrhea and/or WBC/RBC in stool • except in mild inflammation like viral/microscopic colitis • Often accompanied by rapid motility/abdominal cramps • Urgency/tenesmus if rectum is involved

34. Clues to Inflammatory Diarrhea on Gram Stain: Presence of WBC/RBC; Monotonic Bacterial Population PMNs RBCs

35. Definitions • Acute diarrhea <14 days duration • Persistent diarrhea >14 days • Chronic diarrhea >30 days • Inflammatory diarrhea fever, tenesmus, fecal leukocytes, colonic bleeding • Non-inflammatory diarrhea • Nosocomial diarrhea (>3 days after admission)

36. Principles of Evaluation • Majority of cases resolve in 1-2 days without any sequelae • Stool culture has a low yield • Specific diagnosis is useful for antimicrobial treatment decisions but not supportive treatment

37. Non-inflammatory? • CMV • C. Difficile • ETEC • Yersinia • Shigella

38. Acute Diarrhea Subtypes • Organik (Nonfunctional) • Noninflammatory: Norwalk, Rota, Giardia, Staf. Aureus, B. Cereus, C. Perfringens, ETEC, Vibrio cholerae • İnflammatory: CMV, EHEC, C. Difficile, Shigella, Salmonella, EIEC, Yersinia, E. Hystolytica • İnorganik (Fonctunial)

39. The Big 4 found on 233,000 stool cultures • Camphylobacter 1.4 % • Salmonella 0.9% • Shigella 0.6% • E coli O157:H7 (STEC) 0.3% Total yield from stool cultures is 5.8%

40. Other agents • Norwalk virus • Norovirus • CMV (HIV, elderly) • Various E coli strains (traveller’s diarrhea) • Vibrio (shellfish, water) • Giardia (persistent diarrhea) • Cryptosporidium (farms) • Isosporia • Entamoeba histolytica • Cyclospora • Yersinia (lymphadenitis) • Aeromonas

42. Case 1 A 75 yo frail elderly woman is brought to ED with dizziness and diarrhea for 6 days. She has been having temperatures of 37.3, cramps and some blood and mucus in her stool. She has a cat. She rarely eats out and has not traveled.

43. What is the most likely cause of her illness? • Salmonella • Giardia • Shigella • E. coli O157:H7 • Campylobacter • Rotovirus

44. Camphylobacter-1

45. Campylobacter-2 • Most common bacterial cause of diarrhea • Animal reservoir (all but poultry mostly) • Incubation period is 1-7 days depending upon dose (10,000 organisms) • Infects jejunum, ileum, colon • Fever, water-pus-blood in stool • 1% bacteremia

47. Patients with Campylobacter infection can present with clinical manifestations mimicking other diseases (eg, "pseudoappendicitis" and colitis). • A variety of acute complications can occur. There are two major late onset complications of Campylobacter infection: reactive arthritis and Guillain-Barré syndrome (GBS)

48. Campylobacter-3 • Illness lasts 1-7 days but in 15% >7 days • Relapses in 5-10% if not treated • Diagnosis: gram stain of stool, darkfield microscopy, culture • Therapy: erythromycin, azithromycin, cipro (resistance climbing)

50. Campylobacter-4 • Campylobacter is implicated in 1/3 of cases of Guilliane-Barre’ syndrome • Organism produces a ganglioside mimic (autoimmune response) • Risk: 1/3200 cases of Campylobacter