1. CHRONIC DIARRHEA

2. Chronic Diarrhea
Chronic 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.

3. ETIOLOGY Osmotic diarrhea
Mg, PO4, SO4 ingestion
Carbohydrate malabsorption

4. ETIOLOGY Fatty diarrhea
Malabsorption syndromes
Mucosal diseases
Short bowel syndrome
Postresection diarrhea
Small bowel bacterial overgrowth
Mesenteric ischemia
Maldigestion
Pancreatic exocrine insufficiency
Inadequate luminal bile acid

5. Inflammatory diarrhea
Inflammatory bowel disease
Ulcerative colitis
Crohn's disease
Diverticulitis
Ulcerative jejunoileitis

6. Inflammatory diarrhea
Infectious diseases
Pseudomembranous colitis
Invasive bacterial infections
Tuberculosis, yersinosis, others
Ulcerating viral infections
Cytomegalovirus
Herpes simplex
Amebiasis/other invasive parasites

7. Inflammatory diarrhea
Ischemic colitis
Radiation colitis
Neoplasia
Colon cancer
Lymphoma

8. Secretory diarrhea Laxative abuse (nonosmotic laxatives)
Post-cholecystectomy (from bile salts)
Congenital syndromes (chloridorrhea)
Bacterial toxins
Ileal bile acid malabsorption
Inflammatory bowel disease
Ulcerative colitis
Crohn's disease
Microscopic (lymphocytic) colitis
Collagenous colitis
Diverticulitis
Vasculitis
Drugs and poisons

9. Secretory diarrhea Disordered motility Postvagotomy diarrhea
Postsympathectomy diarrhea
Diabetic autonomic neuropathy
Hyperthyroidism
Irritable bowel syndrome

10. Secretory diarrhea Neuroendocrine tumors Gastrinoma VIPoma
Somatostatinoma
Mastocytosis
Carcinoid syndrome
Medullary carcinoma of thyroid

11. Secretory diarrhea Neoplasia Colon carcinoma Lymphoma Villous adenoma
Addison's disease
Epidemic secretory (Brainerd) diarrhea
Idiopathic secretory diarrhea

12. HISTORY
The 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. HISTORY
A 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. HISTORY
The 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 skin
Mouth ulcers
Thyroid masses
Wheezing

19. PHYSICAL EXAMINATION Arthritis Heart murmurs
Hepatomegaly or abdominal masses
Ascites, and edema
Anorectal 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
IBS
Idiopathic inflammatory bowel disease
Malabsorption syndrome
Chronic infections
Idiopathic secretory diarrhea (which also may be a chronic, but eventually self-limited, infection).

22. CAUSES OF CHRONIC DIARRHEA IN LESS DEVELOPED CONTRIES
Chronic bacterial
Mycobacterial
Parasitic infections
are 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 inflammation
Eosinophilia 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 cultures
pH, electrolytes and minerals, and laxatives

25. QUANTITATIVE STOOL COLLECTION AND ANALYSIS
General principles:Quantitative stool collection fixed diet 80 to 100 g of fat
Fecal weight
Electrolytes and calculation of an osmotic gap
Measured osmolality
Fecal pH
Fecal fat concentration and output
Tests for fecal carbohydrate
Analysis for laxative
Tests for protein-losing enteropathy

26. BLOOD AND URINE TESTS
Analysis 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 antibodies
Perinuclear antineutrophil cytoplasmic antibodies
HLA typing
Quantitation of serum immunoglobulin concentrations
Antibodies to HIV and Entamoeba histolytica

29. ENDOSCOPIC EXAMINATION AND MUCOSAL BIOPSY
Sigmoidoscopy and colonoscopy
Upper tract endoscopy

30. RADIOGRAPHY Barium radiography Mesenteric angiography
Computed tomography

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 overgrowth
An 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 fistula
The presence of visible or occult blood on digital examination
Abdominal masses or abdominal pain
Evidence of malabsorption (such as wasting, physical signs of anemia

36. SUMMARY AND RECOMMENDATIONS
Scars indicating prior abdominal surgery
Lymphadenopathy (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.