1 / 44

DIARRHEA

DIARRHEA. A pathophysiological Approach to Diagnosis and Treatment Prof. J. Zimmerman Gastroenterology Hadassah-Hebrew University Medical Center. Diarrhea = Increased loss of water from the GI tract. Diarrhea is a common complaint.

garvey
Télécharger la présentation

DIARRHEA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. DIARRHEA A pathophysiological Approach to Diagnosis and Treatment Prof. J. Zimmerman Gastroenterology Hadassah-Hebrew University Medical Center

  2. Diarrhea = Increased loss of water from the GI tract

  3. Diarrhea is a common complaint. • In the USA, >3.5 million outpatient visits for diarrhea occur each year.

  4. About 10 liters of fluid pass daily through the GI Tract Volume, ml/day

  5. 6 L absorbed 2.5 L absorbed 10 L 1.4 L absorbed 4 L 1.5 L JEJUNUM ILEUM COLON 0.1 L

  6. Water Absorption in the GI Tract • Water movement in the GI tract is passive and follows osmotic gradients. • The efficiency of water absorption is highest in the colon. • The normal colon can absorb as much as 4-5 L of water daily.

  7. Motility of the Intestine and Colon • Normal motor functions are essential for absorption. • Regulated gastric and ileal emptying facilitate reabsorption of electrolytes and fluid. • Normally, the transit time through the small bowel is about 3 hours.

  8. DEFINITIONS OF DIARRHEA • As a symptom: Abnormal frequency: > 3 bowel movements/day; Abnormal consistency: increased stool fluidity; • As a sign: Stool weight >200 g/day;

  9. “Diarrhea” must be distinguished from: • Hyper defecation: Passage of stool of a normal consistency ≥3 times/day; AND FROM • Incontinence

  10. CLINICAL CLASSIFICATION OF DIARRHEA • BY TIME COURSE (ACUTE vs. CHRONIC); • BY VOLUME (LARGE vs. SMALL); • BY PATHOPHYSIOLOGY (OSMOTIC vs. SECRETORY); • BY STOOL CHARACTERISTICS (WATERY, FATTY or INFLAMMATORY); • BY EPIDEMIOLOGY AND CLINICAL BACKGROUND (TRAVEL, ANTIBIOTICS, etc.);

  11. ACUTE DIARRHEA (< 4 week duration): Most Likely Causes • Infection; • Food poisoning; • Medications; • Initial presentation of chronic diarrhea;

  12. INFECTIONS THAT CAUSE DIARRHEA • Bacteria • Shigella, salmonella, campylobacter jejuni, C. difficile; E. coli, vibrio, aeromonas, yersinia • Viruses • Rotavirus, adenovirus, norovirus • Parasites/protozoa • Giardia, E. histolytica, cryptosporidium, microsporidia, cyclospora.

  13. MEDICATIONS THAT CAUSE DIARRHEA (1) • Acid reducing agents (PPI, H2 blockers) • Antacids • Antiarrhythmic (quinidine) • Antibiotics • Anti-inflammatory (NSAIDs) • Antihypertensives ( -blockers)

  14. MEDICATIONS THAT CAUSE DIARRHEA (2) • Antineoplastic agents • Antiretroviral agents • Colchicine • Heavy metals • Prostaglanding analogs (misoprostol)

  15. Workup of Diarrhea:Obey Sutton’s Law Willie Sutton 1901-1980

  16. Stool Examination in Diarrhea • Microscopy (WBC, RBC, parasites); • Cultures; • C. difficile toxin (when appropriate); • Giardia antigen (if appropriate); • IN CHRONIC DIARRHEA: • Occult blood; • Fecal fat; • Stool [Na+] and [K+]; • pH (if < 6 indicates CHO malabsorption) ; • Laxative screen;

  17. Diagnostic Importance of Fecal WBC Abundant WBCNo or few WBC Infections: dysentery viral C. difficile, ameba food poisoning IBD medications Ischemia laxative abuse Irradiation steatorrhea

  18. CHRONIC DIARRHEA WATERY FATTY INFLAMMATORY

  19. CHRONIC WATERY DIARRHEA • Osmotic • Secretory

  20. Water Transport in the GI Tract • The intestinal epithelium cannot maintain an osmotic gradient. • The luminal content from the duodenum to the rectum is iso-osmotic (about 290 mOsmol/kg) .

  21. OSMOTIC DIARRHEA Caused by the presence of unusual amount of poorly absorbable, osmotically active solute in the lumen

  22. Causes of Osmotic Diarrhea • Disaccharidase deficiency; • Monosaccharide malabsorption (fructose-corn syrup in soft drinks); • Ingestion of nonabsorbable materials CHO: sorbitol, lactulose, mannitol Minerals: MgSO4, Na2SO4, Na citrate, antacids • Generalized malabsorption

  23. SECRETORY DIARRHEA Intestinal ion secretion or inhibition of normal active ion absorption

  24. Causes of Secretory Diarrhea • Enterotoxins (cholera, E. coli); • Secretagogues elaborated by tumors (VIP, calcitonin); • Laxatives (ricinoleic acid, phenol-phthalein, oxyphenisatin, aloe, senna); • Bile acids/ FFA (in the colon); • Congenital defects;

  25. Differentiation between Osmotic and Secretory Diarrhea • Effect of fasting; • Volume; • Stool electrolytes and osmotic gap;

  26. CHARACTERISTICS OF OSMOTIC AND SECRETORY DIARRHEA OSMOTICSECRETORY • Volume, L/day: <1 >1 • Fasting (48 hrs): stops continues

  27. Calculation of Stool Osmotic Gap • The osmolarity of fecal fluid as it exits the rectum is close to that of plasma, i.e. 290 mOsmol/Kg. • The osmolarity of fecal fluid can be estimated from the ion concentrations: ([Na+] + [K+]) x 2 • An osmotic gap is the difference between this value and 290. A gap of up to 50 is normal.

  28. OSMOTIC AND SECRETORY DIARRHEA:FECAL FLUID ANALYSIS OSMOTICSECRETORY • [Na+], meq/L 30 100 • [K+], meq/L 30 40 • [Na+]+[K+] 60 140 • 2x([Na+]+[K+]) 120 280 • Solute gap 170 10

  29. 300 250 200 OSMOLALITY, mOsmol/Kg X Anions 150 K Na 100 50 0 Secretory Osmotic

  30. Osmotic and Secretory Diarrhea • In secretory diarrhea, calculated stool osmolarity is close to 290. The osmotic gap is <50. • In osmotic diarrhea, the stool osmolarity, as estimated from the fecal ion concentrations, is lower by more than 50 from a value of 290.

  31. ABNORMAL MOTILITY AND DIARRHEA • BOTH A RAPID AND A SLOW TRANSIT TIME MAY CAUSE DIARRHEA. • A RAPID TRANSIT TIME PREVENTS ADEQUATE TIME FOR ABSORPTION (INTESTINAL HURRY). • THE MECHANISM INVOLVES DYSFUNCTION OF THE ENTERIC NERVOUS SYSTEM. • EXAMPLES: DIABETES, POST- VAGOTOMY, AMYLOIDOSIS, IBS.

  32. ABNORMAL MOTILITY AND DIARRHEA (2) • SLOW TRANSIT TIME PROMOTES BACTERIAL OVERGROWTH AND MAY CAUSE MALABSORPTION AND DIARRHEA.

  33. COMPLEX DIARRHEA • Many of the clinically significant diarrheas are complex and have both osmotic and secretory components.

  34. Chronic Diarrhea ( >4 weeks’ duration): Most Likely Causes • Lactase deficiency; • IBS; • IBD; • Infections, mainly parasitic; • Medications and food supplements; • Previous surgery; • Endocrine: DM, hyperthyroidism, Addison’s disease;

  35. Diarrhea Evaluation (1) • Dietary history: Intake of lactose, sorbitol, fructose, caffeine; • Medications: antacids, antibiotics, quinidine, colchicine, Fe, etc. • Abdominal pain; • Tenesmus, rectal bleeding, mucus; • Intermittent diarrhea and constipation; • Nocturnal diarrhea; • Exposure to infectious agents (travel, sexual preferences);

  36. Diarrhea Evaluation (2) • Past surgical procedures (vagotomy, gastrectomy, cholecystectomy, others); • Desire to reduce weight; • Family history (cancer, IBD, celiac);

  37. Clues to diagnosis-Additional Symptoms SxDx • Fever infection, IBD, TB, Ly • Weight loss malabsorption, cancer, thyrotoxicosis • Flushing Carcinoid

  38. Clues to diagnosis-Associated Diseases DISEASEDx • Liver disease IBD, cancer • Chr. Lung disease CF • Peptic ulcer ZE syndrome • Frequent infections Ig deficiency

  39. Clues to diagnosis-Physical Findings FindingSuggested Dx • Arthritis IBD, infection, Whipple’s disease • Lymphadenopathy Ly, AIDS, Whipple • Neuropathy DM, amyloid • Postural hypotension DM, Addison

  40. Diarrhea EvaluationPhysical Examination SEVERITY CAUSE HYPOVOLEMIA? FEVER? ABDOMINAL FINDINGS?

  41. Diarrhea EvaluationPhysical Examination SEVERITY CAUSE • Clubbing; • Abdominal mass or • tenderness; • Perianal disease; • Rectal examination

  42. Chronic Diarrhea Exclude medications and surgery Blood Features Pain No blood; p.r. Suggest relieved features of malabsorption with BM malabsorption Colonoscopy small bowel Bx ?IBS ?CHO malabsor + Bx etc. Screen lactose BT

  43. REFERENCE • Sleisenger and Fordtran’s Gastrointestinal and liver disease. Chapter on diarrhea contains many useful tables of DD’s of diarrhea in different clinical settings.

More Related