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Add as Friendchronic diarrhea

by: drkrm2003

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3 : Common complaint to primary care physicians and gastroenterologists Complex differential diagnosis Wide variety of available tests Accurate diagnosis may be elusive Most recommendations for evaluation and therapy based on expert opinion (referral bias) Systematic ,common-sense approach yields answer in most cases ( > 90%)
4 : Is it “Chronic”? Is it “Diarrhea”? No consensus definition Four-week cutoff: Most acute (infectious) diarrheas would have resolved; 6-8 weeks better distinction Increased frequency of stool ( > 3/day) is hallmark Most patients consider increased liquidity as essential feature Stool weight > 200 g/day: Not absolute criterion! Fecal incontinence: Needs to be excluded and managed as incontinence, not diarrhea
5 : Daily intake and endogenous secretion and absorption Endogenous secretions 7000 ml % absorbed 8800/9000=98%
6 : The amount of fluid absorbed differs throughout the intestine Intake 2 liter Stool <200 ml Duodenum / jejunum ~5.5 L Ileum ~ 2 L Colon – Rectum ~ 1.3 L
7 : Mechanism of Diarrhea 1) Osmotic load within the intestine resulting in retention of water within the lumen 2) Excessive secretion of electrolytes and water into the intestinal lumen 3) Exudation of fluid and protein from the intestinal mucosa 4) Altered intestinal motility resulting in rapid transit through the colon
8 : Osmotic Diarrhea Occurs when poorly absorbed material retains fluid within the intestinal lumen Occurs in patients with malabsorption or lactose intolerance in which undigested sugars accumulate in the intestinal lumen exerting a considerable osmotic load Magnesium-containing laxatives and antacids (Maalox) probably produce diarrhea through a similar mechanism
9 : Secretory Diarrhea The intestinal mucosa secretes ? amounts of water and electrolytes under the stimulation of a variety of substances Cholera and enterotoxigenic E. coli Bile acids and long chain fatty acids (postileal resection, Crohn’s disease, malabsorption syndromes) Gastrointestinal hormones (VIPoma, gastrinoma, carcinoid) – treat with octreotide, somatostatin analogue Anthraquinone laxatives Mechanism: Agents ? intracellular cAMP? ?secretion (Na+K+ ATPase is also inhibited)
10 : Exudative Diarrhea Results from the outpouring of blood protein, or mucus from an inflamed or ulcerated mucosa Ulcerative colitis Crohn’s disease Invasive infections Infiltrative disorders like Whipple’s disease Lymphoma
11 : Motility Disorders May or may not lead to diarrhea Irritable bowel syndrome (IBS) – a motor disorder that causes abdominal pain & altered bowel habits with diarrhea predominating Diabetes mellitus – neurogenic dysfunction Scleroderma – stasis of the bowel with resultant bacterial overgrowth, steatorrhea and diarrhea
12 : Practical approach
13 : History Define patient’s complaint of diarrhea (change in consistency, presence of urgency or incontinence) Stool characteristics (blood, mucus, oil, pus, food particles) and volume Duration, pattern of onset Relation to prandial state Nocturnal diarrhea Weight loss Travel history Risk factors for HIV infection Dietary profile and medication review Family history of IBD Other systemic symptoms
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15 : Physical examination More helpful to determine severity rather than etiology Hemodynamics, temperature, signs of toxicity Helpful clues:
16 : CHRONIC DIARRHEA Etiology The causes of chronic diarrhea may be grouped into six major pathophysiologic categories
17 : 1-Malabsorptive Conditions The major causes of malabsorption are small mucosal intestinal diseases, intestinal resections, lymphatic obstruction, small intestinal bacterial overgrowth, and pancreatic insufficiency In patients with suspected malabsorption, quantification of fecal fat should be performed
18 : 2-Secretory Conditions Increased intestinal secretion or decreased absorption results in a watery diarrhea that may be large in volume (1–10 L/d) but with a normal osmotic gap Here is little change in stool output during the fasting state. Major causes include endocrine tumors (stimulating intestinal or pancreatic secretion), bile salt malabsorption (stimulating colonic secretion), and laxative abuse
19 : 3-Inflammatory Conditions Diarrhea is present in most patients with inflammatory bowel disease (ulcerative colitis, Crohn's disease, microscopic colitis). A variety of other symptoms may be present, including abdominal pain, fever, weight loss, and hematochezia
20 : 4-Motility Disorders Abnormal intestinal motility secondary to systemic disorders or surgery may result in diarrhea due to rapid transit or to stasis of intestinal contents with bacterial overgrowth resulting in malabsorption
21 : 5-Chronic Infections Chronic parasitic infections may cause diarrhea. Although the list of parasitic organisms is a long one, agents most commonly associated with diarrhea include the protozoans Giardia, E histolytica, Cyclospora, and the intestinal nematodes Immunocompromised patients, especially those with AIDS, are susceptible to a number of infectious agents that can cause acute or chronic diarrhea Chronic diarrhea in AIDS is commonly caused by Microsporida, Cryptosporidium, cytomegalovirus, Isospora belli, Cyclospora, and Mycobacterium avium complex.
22 : 6-Factitial Diarrhea Approximately 15% of patients with chronic diarrhea have factitial diarrhea caused by surreptitious laxative abuse or factitious dilution of stooll
23 : Stool Analysis Directed testing for confirmation based on clinical suspicion Categorize diarrhea into watery, inflammatory, fatty Timed collection is best, spot tests on random stool sample more practical - Occult blood - White blood cells - pH - Sudan stain for fat - Cultures - Laxative screen - Electrolytes, osmolality
24 : Occult blood and white blood cells: - Primarily define inflammatory diarrhea - Wright stain: Sensitivity 70%, specificity 50% for leukocytes - Fecal calprotectin and lactoferrin less operator dependent, but test characteristics in chronic diarrhea not well defined pH: - Low pH (< 6) generally indicative of carbohydrate malabsorption
25 : Sudan stain: - Fatty diarrhea (steatorrhea) - Gold standard: Quantitative estimation of stool fat on collected specimen - Qualitative estimation feasible on random sample, - Semiquantitative methods (number and size of fat globules) correlate well with quantitative collection
26 : Stool cultures: - Infection: Usually inflammatory diarrhea - Bacterial infection rarely cause of chronic diarrhea in immunocompetent host -Routine cultures are low yield and not recommended (but done anyway!) - Special techniques for Aeromonas and Plesiomonas - Ova and Parasites - Always consider giardiasis (stool ELISA for Giardia antigen)
27 : Laxative screen: - High index of suspicion - Stool for bisacodyl and phenolphtalein -urine for anthraquinones - Confirm on another sample before confronting patient
28 : Stool electrolytes: Stool osmotic gap: 290 – 2([Na+] + [K+]) - Gap < 50 mOsm/Kg: Pure Secretory diarrhea - Gap > 125 mOsm/Kg: Pure osmotic diarrhea - Gap 50-125 mOsm/kg: Mixed or mild carbohydrate malabsorption Measured stool osmolality: - Not used to calculate gap - Useful in cases of unexplained diarrhea - Low measured stool osmolality (< 290 mOsm/Kg) suggestive of contamination with water or dilute urine
29 : Blood Tests Routine laboratory tests–CBC, serum electrolytes, liver function tests, calcium, phosphorus, albumin, TSH, total T4, beta-carotene, and prothrombin time should be obtained. Anemia occurs in malabsorption syndromes (vitamin B12, folate, iron) and inflammatory conditions. Hypoalbuminemia is present in malabsorption, protein-losing enteropathies, and inflammatory diseases. Hyponatremia and non–anion gap metabolic acidosis may occur in profound secretory diarrheas. Malabsorption of fat-soluble vitamins may result in an abnormal prothrombin time, low serum calcium, low carotene, or abnormal serum alkaline phosphatase
30 : Other laboratory tests In patients with suspected secretory diarrhea, serum VIP (VIPoma), gastrin (Zollinger-Ellison syndrome), calcitonin (medullary thyroid carcinoma), cortisol (Addison's disease), and urinary 5-HIAA (carcinoid syndrome) levels should be obtained Proctosigmoidoscopy With Mucosal Biopsy: Examination may be helpful in detecting inflammatory bowel disease (including microscopic colitis) and melanosis coli, indicative of chronic use of anthraquinone laxatives.
31 : Imaging Calcification on a plain abdominal radiograph confirms the diagnosis of chronic pancreatitis. An upper gastrointestinal series or enteroclysis study is helpful in evaluating Crohn's disease, lymphoma, or carcinoid syndrome. Colonoscopy is helpful in evaluating colonic inflammation due to inflammatory bowel disease. Upper endoscopy with small bowel biopsy is useful in suspected malabsorption due to mucosal diseases. Upper endoscopy with a duodenal aspirate and small bowel biopsy is also useful in patients with AIDS and to document Cryptosporidium, Microsporida, and M avium-intracellulare infection. Abdominal CT is helpful to detect chronic pancreatitis or pancreatic endocrine tumors.
32 : Chronic organic diarrhea Chronic Fatty Diarrhea – malabsorption syndromes Chronic Inflammatory Diarrhea Chronic Watery Diarrhea Secretory Diarrhea Osmotic Diarrhea Drug-Induced Diarrhea
33 : Infectious Diarrhea Endocrine diarrhea Functional Diarrhea (diagnosis of exclusion) Irritable Bowel Syndrome
34 : Chronic Fatty Diarrhea Steatorrhea usually defined as loss of fat of > 7 g per 24 hours; however 7-14 g range has poor specificity Test may be compromised by orlistat and olestra Three major causes: 1. Pancreatic exocrine insufficiency (chronic pancreatitis) 2. Mucosal diseases (celiac sprue, small bowel bacterial overgrowth) 3. Lack of bile (advanced primary biliary cirrhosis) Clue: Fecal fat concentration > 9.5 g per 100 g suggestive of pancreatic or biliary cause Exclude mucosal disease first, then evaluate pancreas (CT, MRCP, EUS) Elderly, B12 deficiency, low albumin, previous partial gastrectomy, small bowel diverticula: Suspect Small bowel bacterial overgrowth Pancreatic function tests not commonly used Empiric trial of pancreatic enzyme supplementation
35 : Chronic Inflammatory Diarrhea Important considerations: - IBD - Infection (C. difficile, CMV, TB, amebiasis) - Ischemia - Radiation enteritis - Neoplasia Conditions may produce watery secretory diarrhea Diagnosis: Radiographic and endoscopic techniques
36 : Chronic Watery Secretory Diarrhea All patients who undergo sigmoidoscopy or colonoscopy should have biopsies obtained to exclude microscopic colitis Colonoscopy preferred: Intubation of terminal ileum, screening for neoplasia, right-sided disease (collagenous colitis) Upper endoscopy with small bowel biopsies to exclude celiac sprue Small bowel radiographs: IBD, tumors, fistula, short-bowel syndrome CT scan to assess small and large bowel, and pancreas Endocrine diarrhea: RARE, even among patients with chronic diarrhea Bile acid malabsorption: Controversial Trial of bile acid sequestrant reasonable diagnostic/therapeutic step
37 : Chronic Watery Osmotic Diarrhea Magnesium ingestion: - Stool concentration > 90 meq/L - Intentional (laxative abuse) or accidental (antacids, mineral supplements) Carbohydrate malabsorption: - Lactase deficiency - Fructose intolerance (high fructose corn syrup) - Sugar alcohols used as artificial sweeteners (sorbitol, mannitol)
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