chronic diarrhea: approach to the patient diagnostic evaluation must be rationally directed by a...
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Chronic Diarrhea:Approach to the Patient
• diagnostic evaluation must be rationally directed by a careful history and physical examination
• history, physical examination, and routine blood studies– characterize the mechanism of diarrhea– identify diagnostically helpful associations– assess the patient's fluid/electrolyte and nutritional status
• onset, duration, pattern, aggravating (especially diet) and relieving factors, and stool characteristics of the diarrhea
• note presence or absence of fecal incontinence, fever, weight loss, pain, certain exposures (travel, medications, contacts with diarrhea), and common extraintestinal manifestations (skin changes, arthralgias, oral aphthous ulcers)
Chronic Diarrhea:Approach to the Patient
• family history of IBD or sprue
• physical findings may offer clues such as a thyroid mass, wheezing, heart murmurs, edema, hepatomegaly, abdominal masses, lymphadenopathy, mucocutaneous abnormalities, perianal fistulae, or anal sphincter laxity
• peripheral blood – leukocytosis, elevated sedimentation rate, or C-reactive protein
suggests inflammation– anemia reflects blood loss or nutritional deficiencies– eosinophilia may occur with parasitoses, neoplasia, collagen-vascular
disease, allergy, or eosinophilic gastroenteritis
• blood chemistries may demonstrate electrolyte, hepatic, or other metabolic disturbances
• measuring tissue transglutaminase antibodies may help detect celiac disease
INITIAL MANAGEMENT BASED ON ACCOMPANYING SYMPTOMS OR FEATURES
EVALUATION BASED ON FINDINGS FROM A LIMITED AGE APPROPRIATE SCREEN FOR
ORGANIC DISEASE
Chronic Diarrhea
Chronic Diarrhea
• Diarrhea lasting > 4 weeks
Major Causes of Diarrhea According to Predominant Physiologic Mechanism
Chronic Diarrhea
Secretory
Osmotic
Steatorrheal
Inflammatory
Dysmotility
Factitial
Secretory Causes of Diarrhea
• Due to derangements in fluid and electrolyte transport across the enterocolonic mucosa.
• Characterized by a watery, large volume fecal outputs that are typically painless and persist with fasting.
• No fecal osmotic gap.
Secretory Causes of Diarrhea
Medications Hormones
Stimulant laxatives
Chronic ethanol consumption
Environmental toxins
Metastatic GI carcinoid tumors
Primary bronchial carcinoids
Gastrinoma
Pancreatic cholera
VIPoma
Medullary carcinoma of the thyroid
Systemic mastocytosis
Colorectal villous adenoma
Secretory Causes of Diarrhea
Bowel Resection, Mucosal Disease, Enterocolic Fistula
Congenital Defects in Ion Absorption
Congenital chloridorrhea
Addison’s Disease
Osmotic Causes of Diarrhea
• When ingested, poorly absorbable, osmotically active solutes draw enough fluid into the lumen to exceed the resorptive capacity of the colon
• fecal water output increases in proportion to such solute load
• Ceases with fasting or with discontinuation of the causative agent
Osmotic Causes of Diarrhea
Osmotic laxatives
Magnesium containing antacidsHealth supplements
laxatives
Carbohydrate Malabsorption
Acquired or congenital defects in brush border disaccharidases and other enzymes
Lactase deficiency
Steatorrheal Causes of Diarrhea• Increased in fecal output is caused by the
osmotic effects of fatty acids, especially after bacterial hydroxylation and to a lesser extent by a neutral fat
• Quantitatively: stool fat>7g/d• Rapid transit diarrhea may result in fecal fat up
to 14g/d• Daily fecal fat averages
– 15-25g with SI diseases – >32 g with pancreatic exocrine insufficiency
Steatorrheal Causes of Diarrhea
Intraluminal Maldigestion
Chronic pancreatitisCystic fibrosis
Pancreatic duct obstructionsomatostatinoma
Mucosal Maldigestion
Celiac diseaseTropical sprue
Whipple’s diseaseMycobacterium avium
intracellulare infection in AIDS patient
AbetalipoprotenemiaGiardia infection
Colchicine, cholestyramine, neomycin
Chronic schemia
Steatorrheal Causes of Diarrhea
Postmucosal Lymphatic Obstruction
Congenital intestinal lymphangiectasia
Acquired lymphatic obstruction secondary to trauma, tumor, or
infection
Inflammatory Causes of Diarrhea
• Accompanied by pain, fever, bleeding and other manifestation of inflammation
• Mechanism of diarrhea may be due to exudation, fat malabsorption, disrupted fluid/electrolyte absorption, hypersecretion or hypermotility from release of inflammatory mediators
• Stool analysis: leukocytes or leukocyte derived protein (calprotectin)
Inflammatory Causes of Diarrhea
• with severe inflammation, exudative protein loss can lead to anasarca
• middle aged or older person with chronic inflammatory type diarrhea, especially with blood, should be carefully evaluated to exclude colorectal tumor
Inflammatory Causes of Diarrhea
Idiopathic Inflammatory Bowel Disease
Crohn’s diseaseChronic ulcerative colitis
Microscopic colitis
Primary or Secondary Forms of Immunodefeciency
hypogammaglobulinemia
Inflammatory Causes of Diarrhea
Eosinophilic Gastroenteritis
Hypersensitivity to certain food
Other causes
Radiation enterocolitisChronic graft vs host disease
Behcet’s syndromeCronkite-Canada Syndrome
Dysmotility Causes of Diarrhea
• Rapid transit time may accompany many diarrheas as a secondary or contributing phenomenon, but primary dysmotility is an unusual etiology
• Stool features often suggest a secretory diarrhea, but mild steatorrhea of up to 14 g/d can be produced by maldigestion from rapid transit alone
Factitial Causes• Accounts for up to 15% unexplained
diarrheas• Munchausen syndrome( deception or self
injury) or eating disorders (self administer laxatives alone or in combination with other medication(diuretics)
• Women with histories of psychiatric illness and disproportionately from careers in health care
• Hypotension and hypokalemia
Dysmotility Causes of Diarrhea
• Hyperthyroidism, carcinoid syndrome, certain drugs( PG and prokinetic drugs) may produce hypermotility with diarrhea
• Primary visceral neuropathies or idiopathic acquired intestinal obstruction
• Diabetic diarrhea
• Irritable bowel syndrome