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6. HDS GI Repro > Diarrhea > Flashcards

Diarrhea Flashcards

1
Q

Diarrhea Definition

A

Normal BMs: vary from 3 per day to 3 per week

Multiple definitions for diarrhea are used:

  • ↑ Frequency of stools w/ ↓ consistency and ↑ volume
  • ≥ 3 loose or watery stools
  • Stool weight > 200gm per day (
    • Not very meaningful clinically as people are not weighing their stool
    • May be higher w/ high-fiber diets
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2
Q

Acute vs. Chronic

Diarrhea

A
  • Acute Diarrhea
    • Generally 2 wks or less in duration
  • “Persistent” Diarrhea
    • > 14 days up to 4 wks in duration
  • Chronic Diarrhea
    • Loose stool w/ or w/o ↑ frequency for > 4 wks
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3
Q

Acute Diarrhea

Overview

A
  • > 90% of cases are infectious in etiology
  • ↑ Duration ⇒ ↑ likely to be non-infectious
  • Viral or bacterial cause
  • Frequently self-limited and very common
    • 1 episode/person/yr in Western countries
  • Outbreaks are common
    • Food or water contamination
    • High-risk groups:
      • People who care for infants
      • Small children
      • Travelers
      • Immunocompromised individuals
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4
Q

Acute Diarrhea

Elderly Population

A

Elderly are not more commonly affected

Deaths due to diarrhea occur most commonly in the elderly

  • Physiologic changes
    • Abnormalities in water homeostasis
    • ↓ Thirst perception
  • Volume depletion leads to ↑ risk for falls
    • Orthostatic hypotension
    • Electrolyte disturbances
    • Delirium
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5
Q

Acute Diarrhea

Differential Diagnosis

A
  • Infectious Diarrhea:
    • Pathogens causing mucosal inflammation can range from mild to severe presentation
    • Pts often present w/ watery diarrhea progressing to bloody diarrhea
  • Non-infectious Diarrhea:
    Most of these are more likely to present w/ chronic diarrhea
    • Irritable bowel syndrome
    • Inflammatory bowel disease (IBD)
    • Ischemic bowel disease
      • Ischemic colitis or mesenteric vascular insufficiency
    • Carcinoid syndrome, thyrotoxicosis
    • Partial bowel obstruction
    • Fecal impaction w/ overflow diarrhea
    • Food allergies
    • Medications and over the counter supplements
      • Oral magnesium
      • Donepezil hydrochloride
      • Tube feedings
      • Liquid medications
      • Chewing gum w/ non-absorbable sugars (sorbitol)
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6
Q

Acute Diarrhea

Microbiology

A
  • Viral infections
    • Most common cause
    • Noroviruses, rotaviruses, and adenovirus
  • Bacterial infections
    • Cultures positive in ~ 1.5-5.6% of cases
    • Can cause severe diarrhea
      • Salmonella
      • Campylobacter
      • Shigella
      • Enterotoxigenic E. Coli ⇒ most common cause of acute traveler’s diarrhea
      • Clostridium difficile
  • Protozoa do not frequently cause acute diarrhea
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7
Q

Acute Infectious Diarrhea

Classification

A
  • Classify by clinical presentation as noninflammatory vs. inflammatory
  • A lot of overlap w/ invasive versus noninvasive classification
  • In general (w/ 2 exceptions)
    • Invasive organisms ⇒ inflammatory picture
    • Noninvasive organisms ⇒ noninflammatory picture
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8
Q

Non-inflammatory

Acute Diarrhea

A
  • Etiology
    • Usually viral, but can be bacterial or parasitic
    • Generally these are non-invasive infections agents
  • Pathophysiology
    • More likely to promote intestinal secretion w/o sign. disruption in the intestinal mucosa
  • History and exam findings
    • N/V
    • Absence of fever
    • Abdominal cramps
    • Larger volume, watery, non-bloody stool
  • Lab findings
    • Absence of fecal leukocytes
  • Common pathogens
    • Rotavirus, Norovirus
    • Enterotoxigenic E. coli
    • Vibrio cholerae
    • Giardia, Cryptosporidium
  • Other
    • Generally milder disease
    • Severe fluid loss can occur, especially in malnourished pts
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9
Q

Inflammatory

Acute Diarrhea

A
  • Etiology
    • Generally invasive or toxin-producing bacteria
  • Pathophysiology
    • More likely to disrupt mucosal integrity
    • May lead to tissue invasion and destruction
  • History and exam findings
    • Fever
    • Abdominal pain, tenesmus
    • Smaller volume, bloody stool
  • Lab findings
    • Presence of fecal leukocytes
  • Common pathogens
    *Classified as noninvasive pathogens in micro
    • Salmonella (non-Typhi species), Shigella, Campylobacter
    • Enterohemorrhagic E. coli*
    • Enteroinvasive E. coli
    • Clostridium difficile*
    • Entamoeba histolytica, Yersinia
  • Other
    • Generally more severe disease
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10
Q

Antibiotic-associated Diarrhea

A
  • Pts currently or recently on abx can develop diarrhea
    • Alteration in the normal intestinal flora caused by abx use
  • Watery, non-inflammatory diarrhea
  • DDx is C. difficile
    • See fever, high serum WBC, stool WBCs, etc. w/ C. diff
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11
Q

Acute Diarrhea

History

A
  • Travel Hx
    • Traveler’s diarrhea: acute-onset of diarrhea occurring during or shortly after travel
  • Work exposure (ex. Works in day care center)
  • Pets (ex. Salmonella associated w/ pet turtles)
  • Fever
  • Food consumption or preparation
    • Raw or undercooked meats and dairy products
    • Contaminated fruits and vegetables
  • Pregnancy
    • 20x ↑ risk of developing listeriosis from meat or unpasteurized milk
  • Timing of onset of diarrhea
    • Generally starts within 6 hrs of ingestion of pre-formed toxins (S. aureus, B. cereus, or C. perfringens)
  • Any recent changes in medications
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12
Q

Acute Diarrhea

Evaluation

A
  • Generally clinical investigation not necessary
    • Short duration, good prognosis, and most commonly viral etiology
    • 20-40% of the time no cause will be found when evaluated
  • Indications for evaluation of etiology of acute diarrhea:
    • Profuse watery diarrhea and hypovolemia
    • Frequent small-volume, bloody stools w/ mucus or bloody diarrhea
    • Illness longer than 48 hours
      • Worsening or not improving
    • Hospitalization
    • Recent use of abx
    • Age > 70 years
    • Immunocompromised individual
    • Systemic illness
      • Fever > 101 F o
      • Severe abdominal pain
    • Diarrhea in pregnancy because listeria is a possible cause
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13
Q

Acute Diarrhea

Diagnostic Tests

A
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14
Q

Acute Diarrhea

Treatment

A
  • Supportive treatment (general approach)
    • Oral or intravenous hydration
    • Perspiration replacement drinks (ex. Gatorade) ok if not volume depleted
  • Symptomatic treatment
    • Dietary changes
      • Clear liquids, soft and low-fiber foods ⇒ aids hydration & provide some calories
      • Avoid dairy ⇒ risk of temporary lactose intolerance due to mucosal injury
      • Avoid caffeine and alcohol ⇒ both ↑ intestinal motility
    • Anti-motility agents
      • Ex. Loperamide, diphenoxylate-atropine [Lomotil], tincture of opium
      • Can ↓ frequency of stools
      • Should be used only in acute diarrhea w/ no blood or fever
    • Empiric antibiotics
      • Generally do not give if pt is not severely ill
      • Avoid abx for enterohemorrhagic E. coli
        • No clinical benefit
      • ↑ risk of hemolytic-uremic syndrome due to ↑ release of Shiga toxin
      • No clinical improvement in Non-typhoid Salmonella
        • May actually prolong bacterial clearance
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15
Q

Chronic Diarrhea

Epidemiology

A
  • Chronic diarrhea is common
    • Lifetime prevalence (developed countries) 2-7%
    • Prevalence in elderly 7-14% (w/ functional disorders included)
  • Very broad differential dx
    • Can classify by type
  • Infectious causes are unusual in the US
    • Very common in developing world
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16
Q

Chronic Diarrhea

Classifications

A
  • 5 main cetegories:
    • Secretory
    • Osmotic
    • Steatorrhea
    • Inflammatory
    • Dysmotility
  • Some conditions have fndings from multiple categories
  • Consider factitious causes if etiology remains unclear despite work-up
17
Q

Chronic Secretory Diarrhea

A
  • Description
    • Large volume, watery diarrhea (>1 liter/ day)
    • Continues despite fasting
    • Usually painless
    • Occurs both day and night
    • Uncommon cause of chronic diarrhea
  • Pathophysiology
    • Derangements in fluid and electrolyte transport across the enterocolonic mucosa
  • Differential Diagnosis
    • Drugs, non-osmotic laxatives, bile salts
    • Chronic ethanol ingestion
    • Cholera / bacterial toxins
    • Neuroendocrine tumors: Zollinger-Ellison syndrome (gastrinoma), Vasoactive intestinal peptide-producing tumor (VIPoma), and carcinoid
    • Bowel resection, mucosal disease (ex. Crohn’s) or enterocolic fistula
  • Diagnostic factors
    • Dx usually made by hx and trial of stool monitoring during fasting
    • Little or no osmotic gap (< 50 mOsm/kg)
18
Q

Chronic Osmotic Diarrhea

A
  • Description
    • Watery diarrhea
    • Generally stops w/ fasting
  • Pathophysiology
    • Ingested, poorly absorbable, osmotically active solutes draw more fluid into the colonic lumen than can be absorbed
  • Differential Diagnosis
    • Carbohydrate malabsorption (lactulose or fructose)
    • Osmotic laxatives (Mg, PO4)
    • Sugar alcohols (mannitol, sorbitol, xylitol)
  • Diagnostic factors
    • Dx usually made by careful diet history
    • High osmotic gap (>125 mOsm/kg)
    • Low stool pH suggests carbohydrate malabsorption (due to carb fermentation)
    • High stool Mg output suggests Mg ingestion
19
Q

Steatorrhea

A

Steatorrhea defined by stool fat exceeding the normal 7gm/day

  • Generally malabsorption of fats and nutrients
    • ↑ stool output d/t osmotic effects of fatty acids
    • Congenital
      • Membrane transport defects of small bowel enterocytes
    • Acquired
      • Extensive damage or resection of small bowel causing ↓ absorptive area
  • BM are greasy or oily and foul-smelling
  • Often associated w/ weight loss
  • Can lead to nutritional deficiencies
  • Differential Dx:
    • Intraluminal maldigestion
      • Chronic pancreatitis leading to pancreatic insufficiency (when ≥90% of pancreatic secretory function is lost)
        • Cystic fibrosis or pancreatic duct obstruction
      • Bacterial overgrowth in small intestine
    • Mucosal malabsorption
      • Etiologies including Celiac disease (i.e. celiac sprue), tropical sprue, Whipple’s disease and short bowel syndrome
  • Lab findings depend on severity and which nutrients are deficient
20
Q

Inflammatory Diarrhea

A
  • Bloody, mucous diarrhea w/ frequent, urgent small stools
  • Differential Diagnosis:
    • Inflammatory bowel disease
    • Infectious colitis
    • Invasive bacteria
21
Q

Dysmotility Diarrhea

A
  • Rapid transit often occurs w/ diarrhea as a secondary or contributing phenomenon
    • 1° Dysmotility is unusual etiology of true diarrhea
  • Can have features of secretory diarrhea ± mild steatorrhea
    • Soft to watery stools
  • Differential Diagnosis:
    • Hypermotility
      • Hyperthyroidism, carcinoid syndrome, and drugs (prostaglandins and prokinetic agents)
    • Dysmotility
      • DM (often w/ peripheral and autonomic neuropathies), scleroderma
    • Irritable Bowel Syndrome
22
Q

Irritable Bowel Syndrome (IBS)

Overview and Epidemiology

A
  • “Functional” bowel disorder
  • Characterized by altered bowel habits and abdominal pain
    • Without detectable structural abnormalities
  • Diarrhea and constipation predominant forms
  • Prevalence in North America is 10-15%
  • 2-3x more common in women
    • Women make up 80% of those w/ severe IBS
  • IBS affects all ages but most pts have their first sx before age 45
23
Q

Irritable Bowel Syndrome (IBS)

Clinical Manifestations

A
  • Pain or abdominal discomfort ⇒ key sx
    • Crampy and episodic
    • Relieved w/ defecation
  • Altered bowel habits ⇒ most typical feature
    • Constipation alternating w/ diarrhea ⇒ most common pattern
    • Many w/ constipation or diarrhea as predominate sx
    • Altered BMs interspersed w/ nl stools
    • Urgency and feeling of incomplete evacuation
    • Small volume
    • Mucus in stool (~ 50%)
    • Stops during sleep
    • Exacerbated by emotional stress or eating
  • Abdominal distention
  • ↑ Belching and flatulence
  • Dyspepsia, heartburn, N/V (25-50%)
  • Not consistent w/ IBS:
    • Large-volume diarrhea
    • Bloody diarrhea
    • Nocturnal diarrhea
    • Greasy stool
    • Weight loss
24
Q

Irritable Bowel Syndrome (IBS)

Pathophysiology

A

Poorly understood

Mechanisms proposed:

  • Abnormal gut motor and sensory activity
    • Quantitative differences vs healthy controls
      • Ileum, colon, rectum hyperreactive to stimuli
        • Meals, distention, stress
    • Visceral Hypersensitivity
      • Enhanced perception of visceral events
        • Intestinal contractions and gas
      • Seen in esophagus, stomach, duodenum, and ileum
  • Central neural dysfunction
  • Mucosal inflammation
  • Luminal factors
  • Psychological disturbances and/or stress
    • Sensitive to psychological stress ⇒ sx exacerbation
    • Up to 80% of IBS pts may have psychological sx
  • IBS sx can occur after a GI infection
25
Q

Irritable Bowel Syndrome (IBS)

Diagnosis

A
  • Rome III Criteria
    • Recurrent abd pain or discomfort on 3+ days/month in the last 3 months ass. w/ ≥ 2 of the following:
      • Improvement of pain w/ BM
      • ∆ in frequency of stool
      • ∆ in form or consistency of stool
  • Perform hx and PE (including rectal) to assess for other causes
  • Pt needs further work-up if sx not consistent w/ IBS including:
    • Rectal bleeding, nocturnal or progressive abdominal pain, weight loss
    • Lab abnormalities: anemia, electrolyte disturbances, elevated inflammatory markers;
    • Fhx of IBD or cancer
26
Q

Irritable Bowel Syndrome (IBS)

Treatment

A
  • Dietary modification
    • Careful diet hx for triggers
    • Caffeine, gas-producing foods, fermentable saccharides [fructose, high-fructose corn syrup, wheat], lactose
  • Stool-bulking agents
    • Fiber
  • Physical activity may help
  • Antidiarrheal agents (if diarrhea predominant IBS)
    • Loperamide
  • Antidepressants
    • May help in pts w/ depressive sx
27
Q

Factitious Causes

Diarrhea

A
  • Up to 15% of cases of unexplained diarrhea
  • DDx: Munchausen syndrome or eating disorders
  • Most typical pt is a woman w/ hx of psychiatric illness
    • Disproportionately w/ hx of career in health care
  • May add water or urine to stool, self-administer laxatives w/ or w/o other medications like diuretics
    • Hypotension and hypokalemia are common findings
28
Q

Chronic Diarrhea

History

A
  • Onset and duration
  • Continuous vs. intermittent sx
  • Presence of nocturnal diarrhea
  • Duration of diarrhea
  • Stool characteristics: watery, bloody, greasy
  • Fecal incontinence vs. diarrhea (or both)
  • Aggravating factors
    • Stress
    • Specific foods (ex. Milk)
  • Alleviating factors
    • Diet changes
    • Prescription or OTC medications
  • Prior work-up done
  • Abdominal pain (IBD, IBS, mesenteric vascular insufficiency)
  • Epidemiology
    • Travel
    • Exposure to contaminated food or water
    • Family members w/ similar illness
  • Weight loss (Malabsorption, IBD, ischemia, and neoplasm)
  • Previous operations, radiation therapy
  • Medications and supplements
  • ROS for systemic causes
    • Hyperthyroidism, scleroderma, tumor syndromes, DM
    • Risk factors for HIV or other immunocompromised conditions
  • Hx of eating disorders, secondary gain, or history of malingering
    • Potential markers of factitious diarrhea
29
Q

Chronic Diarrhea

Physical Exam

A

Most likely will not provide a specific dx

May be helpful for fluid status and nutritional status

  • Mouth ulcers or perianal disease ⇒ suggests IBD
  • Rash or flushing
  • Abdominal mass
  • Findings of hyperthyroidism or thyroid mass
30
Q

Chronic Diarrhea

Systemic Labs

A
  • CBC to assess for presence/type of anemia
  • Leukocytosis ⇒ suggests inflammation
  • Eosinophilia can be associated w/ neoplasm, allergy, collagen-vascular diseases, parasitic infection, and eosinophilic gastroenteritis or colitis
  • CMP ⇒ fluid/electrolyte status, nutritional status, liver problems, Dysproteinemia
31
Q

Chronic Diarrhea

Stool Analysis

A

Quantitative stool collection vs spot stool collection

  • Fecal osmotic gap
    • Sodium and potassium concentrations in stool water ([Na+] + [K+])
    • Osmotic diarrhea ⇒ osmotic gap > 125 mOsm/kg
    • Secretory diarrhea ⇒ osmotic gap < 50 mOsm/kg
  • Stool pH
    • Value of < 5.6 consistent w/ carbohydrate malabsorption
  • Fecal occult blood testing
    • ⊕ consistent w/ IBD, neoplasm, celiac disease or other “sprue-like” syndrome
  • Fecal leukocytes
    • Suggest inflammatory diarrhea
  • Excess stool fat
    • Directly measured or w/ Sudan stain
    • Can see large and numerous fat globules if malabsorption or maldigestion
  • Laxative screening
    • Perform if chronic diarrhea w/ no clear diagnosis

6. HDS GI Repro (30 decks)

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