2 Chronic DiarrheaChronic diarrhea, defined as the production of loose stools with or without increased stool frequency for more than four weeks, is a common symptom that has a prevalence in the United States of approximately 3 to 5 percent.Chronic diarrhea may be caused by any one of many conditions.Correlation of data from history, physical examination, laboratory tests, radiographic studies, and endoscopic examinations usually results in an accurate diagnosis.
12 HISTORYThe characteristics of the onset of diarrhea: Whether it was congenital, abrupt, or gradual in onset.The pattern of diarrhea : continuous or intermittent?The duration of symptoms should be identified clearly.
13 HISTORY Travel before the onset of illness, Exposure to potentially contaminated food or water,Illness in other family members should be elicited.Stool characteristics: watery, bloody, or fatty.
14 HISTORY Risk factors for HIV infection Weight loss Occurrence of diarrhea during fasting or at night (suggesting a secretory diarrhea)Family history of IBD
15 HISTORY The volume of the diarrhea The presence of systemic symptoms, which may indicate inflammatory bowel disease (such as fevers, joint pains, mouth ulcers, eye redness)All medications (including over-the-counter drugs and supplements)
16 HISTORYA relevant dietary (use of sorbitol-containing products and use of alcohol)Association of symptoms with specific food ingestion (such as dairy products or potential food allergens)A sexual history
17 HISTORYThe presence or absence of fecal incontinence. Some individuals complain of diarrhea when their major difficulty is disordered continence.
18 PHYSICAL EXAMINATION Extent of fluid and nutritional depletion Flushing or rashes on the skinMouth ulcersThyroid massesWheezing
19 PHYSICAL EXAMINATION Arthritis Heart murmurs Hepatomegaly or abdominal massesAscites, and edemaAnorectal examination: sphincter tone and contractility and the presence of perianal fistula or abscess.
20 Differentiation of chronic diarrhea from irritable bowel syndrome and fecal incontinence IBS :combination of abdominal pain and abnormal bowel habits (constipation, diarrhea, or variable bowel movements) in the absence of other defined illnesses .Patients with painless diarrhea may have a functional process (i.e., without a known organic cause) but should not be characterized as having IBS.
21 CAUSES OF CHRONIC DIARRHEA IN DEVELOPED CONTRIES IBSIdiopathic inflammatory bowel diseaseMalabsorption syndromeChronic infectionsIdiopathic secretory diarrhea (which also may be a chronic, but eventually self-limited, infection).
22 CAUSES OF CHRONIC DIARRHEA IN LESS DEVELOPED CONTRIES Chronic bacterialMycobacterialParasitic infectionsare the most common causes of chronic diarrhea;functional disorders, inflammatory bowel disease, and malabsorption are also common in this setting .
23 ROUTINE LABORATORY TESTS Anemia.Leukocytosis suggests the presence of inflammationEosinophilia is seen with neoplasm, allergy, collagen-vascular diseases, parasitic infestation, and eosinophilic gastroenteritis or colitis.Serum chemistry screening: fluid and electrolyte status, nutritional status, liver problems, and dysproteinemia.
24 SPOT STOOL ANALYSIS Occult blood White blood cells Sudan stain for fat Fecal culturespH, electrolytes and minerals, and laxatives
25 QUANTITATIVE STOOL COLLECTION AND ANALYSIS General principles:Quantitative stool collection fixed diet 80 to 100 g of fatFecal weightElectrolytes and calculation of an osmotic gapMeasured osmolalityFecal pHFecal fat concentration and outputTests for fecal carbohydrateAnalysis for laxativeTests for protein-losing enteropathy
26 BLOOD AND URINE TESTSAnalysis of urine. for laxative identification and for measurement of excretion of 5-hydroxyindole acetic acid (for carcinoid syndrome), vanillylmandelic acid (VMA); for pheochromocytoma, metanephrine (for pheochromocytoma), and histamine (for mast cell disease and foregut carcinoids).If volume depletion or hypokalemia are present, analysis of urine electrolytes can determine whether renal conservation of sodium and potassium is appropriate. If the urinary concentration or output of sodium or potassium is inappropriately high, surreptitious diuretic use may be present and may suggest coexisting laxative abuse.Measurement of urine electrolytes and aldosterone may distinguish hypervolemia from volume depletion in the setting of hypernatremia caused by ingestion of sodium-containing laxatives
27 Vasoactive intestinal polypeptide and other peptide hormones Pancreatic cholera :secretory diarrhea attributable to secretion of (VIP) by a neuroendocrine tumor. It should be suspected if diarrhea of unknown origin has lasted longer than four weeks, has the clinical features of secretory diarrhea, has a volume greater than 1 L/day, is associated with hypokalemia, and causes clinically significant volume depletion.Measurement of calcitonin for the diagnosis of medullary carcinoma of the thyroid, gastrin for suspected Zollinger-Ellison syndrome, and glucagon for the rare patient with a glucagonoma .
28 Serological tests Antinuclear antibodies Antigliadin immunoglobulin Ig A and Ig G antibodies and antiendomysial IgA antibodiesPerinuclear antineutrophil cytoplasmic antibodiesHLA typingQuantitation of serum immunoglobulin concentrationsAntibodies to HIV and Entamoeba histolytica
29 ENDOSCOPIC EXAMINATION AND MUCOSAL BIOPSY Sigmoidoscopy and colonoscopyUpper tract endoscopy
31 PHYSIOLOGICAL TESTS Mucosal absorption Tests of ileal absorptive function Breath tests for physiological testing Tests for bacterial overgrowth
32 TESTS FOR GASTROINTESTINAL FOOD ALLERGY Allergy to food antigens may be the cause of chronic diarrhea in some patients, but documentation of this has been difficult.Reports have described detection of antibodies to food in feces or small intestinal secretions.Serum antibody testing and skin testing are not of proven value in detection of gastrointestinal food allergies.
33 Role of empiric therapy A daycare worker who develops diarrhea after a known outbreak of Giardiasis within the daycare,a patient who develops diarrhea following limited (<100 cm) ileal resection in whom bile acid malabsorption is likely,A patient with known recurrent bacterial overgrowthAn otherwise healthy patient with suspected lactose intolerance in whom relief of symptoms is observed following a temporary trial of a lactose-free diet.When comorbidities limit diagnostic evaluation.
34 SUMMARY AND RECOMMENDATIONS 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
35 SUMMARY AND RECOMMENDATIONS A thorough medical history include findings suggestive of IBD (eg, mouth ulcers, a skin rash, episcleritis, an anal fissure or fistulaThe presence of visible or occult blood on digital examinationAbdominal masses or abdominal painEvidence of malabsorption (such as wasting, physical signs of anemia
36 SUMMARY AND RECOMMENDATIONS Scars indicating prior abdominal surgeryLymphadenopathy (possibly suggesting HIV infection)Abnormal anal sphincter pressure or reflexes (possibly suggesting fecal incontinence).Palpation of the thyroid and examination for exopthalmus and lid retraction may provide support for a diagnosis of hyperthyroidism.
37 SUMMARY AND RECOMMENDATIONS The history and physical examination may point toward a specific diagnosis for which testing may be indicated.As an example, serologic testing for celiac disease would be appropriate in patients with risk factors (such as type 1 diabetes mellitus or a family history of celiac disease).
38 SUMMARY AND RECOMMENDATIONS The minimum laboratory evaluation in most patients should include a complete blood count and differential, thyroid function tests, serum electrolytes, total protein and albumin, and stool occult blood.In addition, most patients require some form of endoscopic evaluation (either sigmoidoscopy, colonoscopy, or sometimes upper endoscopy) depending upon the clinical setting.