Chronic Diarrhea

Aka: Chronic Diarrhea

1. See Also
   1. Acute Diarrhea
   2. Diarrhea in Cancer
   3. Diarrhea in Children
   4. Diarrhea in Pregnancy
   5. Diarrhea in HIV
2. Definitions
   1. Chronic Diarrhea
      1. Persistent Diarrhea with decreased stool consistency >4 weeks
3. Epidemiology
   1. Prevalence: 1-5% of adults
4. Causes: Common
   1. Irritable Bowel Syndrome
   2. Inflammatory Bowel Disease
   3. Celiac Disease
   4. Microscopic Colitis
5. Causes: By Type
   1. Chronic Fatty Diarrhea
      1. Diarrhea due to Malabsorption
   2. Chronic Inflammatory Diarrhea
      1. Infectious Diarrhea
      2. Inflammatory Bowel Disease
   3. Chronic Watery Diarrhea
      1. Secretory Diarrhea
         1. Large volume stools >1 L/day and not better over night or with Fasting
      2. Osmotic Diarrhea
      3. Drug-Induced Diarrhea
      4. Functional Chronic Diarrhea (diagnosis of exclusion)
         1. Small volume stools (<350 ml/day and better over night and with Fasting)
         2. Irritable Bowel Syndrome
6. History
   1. Stool characteristics
      1. Water: Chronic Watery Diarrhea
      2. Blood, pus or mucus: Chronic Inflammatory Diarrhea
      3. Foul, bulky, greasy stools: Chronic Fatty Diarrhea
   2. Age
      1. Young patients
         1. Inflammatory Bowel Disease
         2. Tuberculosis
         3. Functional bowel disorder (Irritable Bowel Syndrome)
      2. Older patients
         1. Colon Cancer
         2. Diverticulitis
   3. Diarrhea pattern
      1. Diarrhea alternates with Constipation
         1. Colon Cancer
         2. Laxative abuse
         3. Diverticulitis
         4. Functional bowel disorder (Irritable Bowel Syndrome)
      2. Intermittent Diarrhea
         1. Diverticulitis
         2. Functional bowel disorder (Irritable Bowel Syndrome)
         3. Malabsorption
      3. Persistent Diarrhea
         1. Inflammatory Bowel Disease
         2. Laxative abuse
   4. Differentiating Small Bowel from Large Bowel
      1. Small Intestine or proximal colon involved
         1. Large stool Diarrhea
         2. Abdominal cramping persists after Defecation
      2. Distal colon involved
         1. Small stool Diarrhea
         2. Abdominal cramping relieved by Defecation
   5. Diurnal variation
      1. No relationship to time of day: Infectious Diarrhea
      2. Morning Diarrhea and after meals
         1. Gastric cause
         2. Functional bowel disorder (e.g. Irritable Bowel Syndrome)
         3. Inflammatory Bowel Disease
      3. Nocturnal Diarrhea (always organic)
         1. Diabetic Neuropathy
         2. Inflammatory Bowel Disease
   6. Weight Loss
      1. Despite normal appetite
         1. Hyperthyroidism
         2. Malabsorption (e.g. Celiac Sprue)
         3. Giardia
         4. Cryptosporidium
         5. Cyclospora
      2. Associated with fever
         1. Inflammatory Bowel Disease
      3. Weight loss prior to Diarrhea onset
         1. Pancreatic Cancer
         2. Tuberculosis
         3. Diabetes Mellitus
         4. Hyperthyroidism
         5. Malabsorption
   7. Medication and dietary intakes
      1. See Drug-Induced Diarrhea
      2. See Foodborne Illness
      3. See Waterborne Illness
      4. High fructose corn syrup
      5. Excessive Sorbitol, Mannitol (chewing gum)
      6. Artificial Sweeteners (e.g. Sucralose, chewing gum, fruit juice, soft drinks)
      7. Excessive coffee or other Caffeine
      8. Alcohol Abuse
      9. Illicit Drug use
   8. Recent travel to undeveloped areas
      1. See Traveler's Diarrhea
      2. See Infectious Diarrhea
7. Red Flags: Suggestive of organic cause
   1. Painless Diarrhea
   2. Recent onset in an older patient
   3. Nocturnal Diarrhea (especially if wakes patient)
   4. Unintentional Weight Loss
   5. Blood in stool
   6. Large stool volumes: >400 grams stool per day
   7. Anemia
   8. Hypoalbuminemia
   9. Erythrocyte Sedimentation Rate increased
8. Signs
   1. Vital Signs
      1. Weight loss (red flag - see causes above)
   2. Eye Exam
      1. Episcleritis (Inflammatory Bowel Disease)
   3. Neck Exam
      1. Lymphadenopathy
      2. Thyromegaly (Hyperthyroidism)
   4. Abdominal exam
      1. Surgical scars
      2. Hypermotility
      3. Hepatomegaly
      4. Abdominal Tenderness
      5. Abdominal mass
   5. Rectal exam
      1. Anal Fistula (Crohn Disease)
      2. Rectal exam (Stool impaction - pseudo-Diarrhea)
      3. Fecal Occult Blood Testing
   6. Skin exam
      1. Dermatitis Herpetiformis (Celiac Sprue)
9. Labs: First-line
   1. Complete Blood Count
   2. Thyroid Stimulating Hormone (TSH)
   3. Serum Electrolytes
   4. Liver Function Tests
   5. C-Reactive Protein
   6. Celiac Sprue testing (esp. if signs of Iron Deficiency)
      1. IgA Tissue Transglutaminase and
      2. Total IgA (with reflex if low to IgG Gliadin)
10. Labs: Stool evaluation
    1. First-Line Tests
       1. Stool Ova and Parasite (2-3 samples)
       2. Giardia lambliaAntigen
          1. Indicated for Diarrhea >7 days and >10 stools/day
       3. Clostridium difficile Toxin
          1. Indicated if recent antibiotics or hospitalization
       4. Fecal fat with sudan stain (abnormal if >14 grams/24 hours)
          1. See Chronic Fatty Diarrhea (Malabsorption)
       5. Fecal lactoferrin or Fecal Calprotectin
          1. See Chronic Inflammatory Diarrhea (e.g. Infectious Diarrhea, Inflammatory Bowel Disease)
          2. Fecal Calprotectin <40 mcg/g and CRP <0.5 reduce Inflammatory Bowel Disease likelihood to<1%
             1. Menees (2015) Am J Gastroenterol 110(3):444-54 [PubMed]
       6. Fecal Occult Blood Test (fecal immunochemistry test)
          1. See Chronic Inflammatory Diarrhea
    2. Other tests
       1. Cryptosporidium stool Antigen test
          1. Indicated in immune compromised state
       2. Fecal Leukocytes
       3. Consider testing stools for Laxative abuse (e.g. Anorexia Nervosa)
          1. Stool Laxative screen (Sodium, Potassium, Magnesium, phosphate, sulfate, Phenolphthalein, Bisacodyl)
       4. Fecal Chemistry Test
          1. Stool pH
             1. pH <5.5 in carbohydrate malabsorption (e.g. Lactose Intolerance)
          2. Fecal Electrolytes (Fecal Sodium and Osmolar Gap)
             1. Differentiates Chronic Watery Diarrhea category (secretory from osmotic)
       5. Quantitative Fecal Fat or Quantitative Sudan Microscopy (24-48 hour)
       6. Stool mass (24 hour)
          1. Quantification of Diarrhea amount
11. Imaging
    1. Options
       1. CT Abdomen and Pelvis
       2. Abdominal MRI with enterography
    2. Abdominal imaging indications
       1. Suspected gastrointestinal structural disease
       2. Red flag features (see above)
       3. Abnormal laboratory testing
       4. Inflammatory Diarrhea
12. Diagnostics
    1. Colonoscopy with biopsy Indications
       1. Persistent or refractory cases without identified cause
       2. Red flag features (see above)
       3. Inflammatory Diarrhea
       4. Formal diagnosis (e.g. Microscopic Colitis)
13. Management
    1. Diarrhea Predominant Irritable Bowel Syndrome is a diagnosis of exclusion
       1. History consistent with Irritable Bowel Syndrome Rome 4 Criteria AND
       2. Reassuring examination AND
       3. Normal laboratory testing AND
       4. No Chronic Diarrhea red flags
    2. Direct to specific causes based on Diarrhea type (Diarrhea may cross categories)
       1. Chronic Fatty Diarrhea
          1. Fecal fat with sudan stain (abnormal if >14 grams/24 hours)
       2. Chronic Inflammatory Diarrhea
          1. Fecal Occult Blood Test (fecal immunochemistry test), Fecal Leukocytes, Fecal Calprotectin or lactoferrin
       3. Chronic Watery Diarrhea
          1. Loose stool without features or Chronic Fatty Diarrhea or Chronic Inflammatory Diarrhea
14. References
    1. Frank in Friedman (1991) Medical Diagnosis, p. 186-9
    2. Schiller in Feldman (2002) Sleisenger GI, p. 136
    3. Burgers (2020) Am Fam Physician 101(8): 472-80 [PubMed]
    4. Juckett (2011) Am Fam Physician 84(10): 1119-26 [PubMed]
    5. Schiller (2004) Gastroenterology 127(1): 287-93 [PubMed]