CHRONIC DIARRHEA

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.

ETIOLOGY Osmotic diarrhea Mg, PO4, SO4 ingestion Carbohydrate malabsorption

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

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

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

Inflammatory diarrhea Ischemic colitis Radiation colitis Neoplasia Colon cancer Lymphoma

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

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

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

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

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.

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.

HISTORY Risk factors for HIV infection Weight loss Occurrence of diarrhea during fasting or at night (suggesting a secretory diarrhea) Family history of IBD

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)

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

HISTORY The presence or absence of fecal incontinence. Some individuals complain of diarrhea when their major difficulty is disordered continence.

PHYSICAL EXAMINATION Extent of fluid and nutritional depletion Flushing or rashes on the skin Mouth ulcers Thyroid masses Wheezing

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.

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.

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).

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 .

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.

SPOT STOOL ANALYSIS Occult blood White blood cells Sudan stain for fat Fecal cultures pH, electrolytes and minerals, and laxatives

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

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

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 .

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

ENDOSCOPIC EXAMINATION AND MUCOSAL BIOPSY Sigmoidoscopy and colonoscopy Upper tract endoscopy

RADIOGRAPHY Barium radiography Mesenteric angiography Computed tomography

PHYSIOLOGICAL TESTS Mucosal absorption Tests of ileal absorptive function  Breath tests for physiological testing  Tests for bacterial overgrowth 

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.

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.

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

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

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.

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).

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.