Diarrhea - Chronic

Chronic diarrhea is defined as increased volume bowel movements persisting for more than 4 weeks. Mechanisms of diarrhea are categorized as increased secretion, decreased absorption, osmotic diarrhea, or abnormal intestinal motility. Many patients mistakenly identify increased frequency or decreased consistency of bowel movements as diarrhea, so the clinician should be certain to identify whether the patient indeed suffers from diarrhea.

Differential Diagnosis

• Diarrhea due to deranged motility presents with alternating diarrhea and constipation, bloating, mucus or blood in the stool, relief of abdominal pain upon defecation, worsening diarrhea with stress
  –IBS: Usually presents in the morning, seldom at night; more common in women; rectal urgency
  –Diabetic neuropathy: Uncontrolled, explosive, postprandial diarrhea; usually seen in patients with neurologic dysfunction and uncontrolled blood sugar
  –Hyperthyroidism
  –Postileal resection
  –Scleroderma
  –Carcinoid syndrome: Diaphoresis and diarrhea
• Secretory diarrhea will persist even after a 48–72 hour fast; stool osmotic gap <50
  –Bacterial gastroenteritis
  –Bile acid malabsorption
  –Colitis
  –Hyperthyroidism
  –Collagen vascular diseases (SLE, MCTD, scleroderma)
  –Neuroendocrine tumors (e.g., VIPoma, gastrinoma, carcinoid)
• Osmotic diarrhea will cease upon fasting; stool osmotic gap >100 mOsm/kg
  –Malabsorption (celiac sprue, nontropical sprue, Whipple's disease)
  –Nonabsorbable substances (e.g., laxatives, lactose, magnesium)

Workup and Diagnosis

• History should include appearance of bowel movements (e.g., bloody, mucusy, greasy, color, consistency), recent travel history, associated symptoms (e.g., abdominal pain), and timing
• Physical examination
  –Blood pressure and pulses, including orthostatics
  –Abdominal, back, genital, and rectal examinations
  –Skin examination (e.g., jaundice, turgor)
  –Signs of dehydration (e.g., loss of jugular pulsations, dry mucous membranes, tenting, orthostatics)
  • Stool examination
    –Blood suggests an inflammatory process
    –WBCs suggest an inflammatory or infectious process
    –72-hour stool collection for fecal fat with Sudan stain will diagnose malabsorption or oil-containing laxatives
    –Stool electrolytes should be measured to calculate stool osmolality [2(K⁺+Na⁺)] and osmotic gap [calculated stool osmolality – 300 ×(normal stool osmolality)]
    –Stool culture (including culture for parasites) is indicated if infectious causes are suspected
    –Stool pH
  • Initial lab tests may include CBC, electrolytes, LFTs, BUN/creatinine, calcium, glucose, urinalysis, and TSH
  • Endoscopy (flexible sigmoidoscopy, colonoscopy with biopsy, or EGD for small bowel biopsy)
  • Breath hydrogen test for lactose intolerance
  • Abdominal CT, small bowel series, and/or barium enema may be indicated

  Treatment

  • Fluid resuscitation: Oral, if possible, or IV (e.g., normal saline or lactated Ringer's)
  • Nonspecific antidiarrheal agents (e.g., loperamide, codeine, tincture of opium) and fiber supplementation may be attempted initially
  • Diabetic neuropathy: Control blood sugar, metoclopramide may be used
  • Irritable bowel syndrome: High-fiber diet, anticholinergics
  • Inflammatory bowel disease is treated with steroids for acute exacerbations and daily prophylactic therapy with 5-aminosalicyclic agents
    –Bowel resection may be necessary
  • Lactose intolerance: Lactose-free diet
  • Diseases of malabsorption: Gluten-free diet, long-term antibiotics
  • Intestinal neoplasm: Consultation with gastroenterology, oncology, and/or surgery
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Book Source Details

• Book Title: In a Page: Signs and Symptoms
• Author(s): Scott Kahan, Ellen G. Smith
• Year of Publication: 2004
• Copyright Details: In a Page: Signs and Symptoms, Copyright © 2004 Lippincott Williams & Wilkins.

Other Book Chapters Related to Diarrhea

Read excerpts from these other book chapters related to Diarrhea:

Copyright Details: In a Page: Signs and Symptoms, Copyright © 2008 Williams & Wilkins.

More About Causes of Diarrhea

• Back to symptom: Diarrhea: Introduction (review 2132 causes)
• Next Book Extract About Diarrhea: Diarrhea – Chronic, No Blood or Weight Loss (In A Page: Pediatric Signs and Symptoms)
• All Book Extracts: All Online Book Extracts for Diarrhea

More About This Book: Title: In a Page: Signs and Symptoms Authors: Scott Kahan, Ellen G. Smith Publisher: Lippincott Williams & Wilkins Copyright: 2004 ISBN: 1-4051-0368-X