Diarrhea
Definition
• Increased liquidity, frequency or decreased
consistency of stools
Mechanisms
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Osmotic Diarrhea
Secretory Diarrhea
Deranged Motility
Exudation
Osmotic Diarrhea
• results from poorly absorbable osmotically
active solutes in the gut lumen
• stops when the patient is fasting
• stool analysis - Inc osmotic gap 290
mosm/kgH2O-2(Na+K)mmol/l
Some Causes of Osmotic
Diarrhea
• Carbohydrate malab
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gluc-galact malab
fructose malab
disaccaridase def
ingestion (poorly
absorbable carbs)
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lactulose
sorbitol
fructose
fiber
• Magnesium-Induced
– Nutritional supplemts
– antacids
– laxatives
• GI Lavage solutions
• Laxative
– sodium citrate
– sodium phophate
– sodium sulfate
Secretory Diarrhea
• Results from abnormal ion transport in
intestinal epithelial cells
• Main categories of secretory diarrhea
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congenital defects of ion absorptive process
intestinal resection
diffuse mucosal disease
abnormal mediators
Secretory Diarrhea
• Diarrhea persist during a fast
• stool Na, K and the accompany anions
account for the stool osmolality (small
osmotic gap)
Some Causes of Secretory
Diarrhea
• Laxatives
– Phenolophthalein, aloe
• Medications
– diuretics
• Toxins
– coffee, tea, cola, ETOH
• Bacterial Toxins
– S.aureus, C.perf +bot,
B.cereus
• Congenital
• Bacterial entertoxins
– V. cholera, C.diff,
Y.enterocol, toxigenic
E. coli
• Endogenous laxatives
– bile acids, LCFA
• Hormone producing
tumors
Deranged Motility
• Enhanced Motility (Intestinal Hurry) decrease contact time of the stool to the
absorptive surface
• Abnormally slow motility may results in
bacterial overgrowth and resultant diarrhea
Exudation
• Results from disruption of the intestinal
mucosa from inflammation or ulceration
• blood, mucus and serum proteins in gut
lumen
– bacillary dysnentery
– Inflammatory bowel disease
Approach to Patients with
Diarrhea
• History
– Characteristics of the onset of diarrhea should
be precisely noted (congenital, abrupt, gradual)
– Pattern of diarrhea should be recorded
(continuous or intermittent)
– Duration of the symptoms
– Epidemiological factors (travel, exposure to
contaminated food or water, illness in other
contacts)
History
– Stool characteristics should be investigated
(watery, bloody, fatty)
– Presence of fecal incontinence
– Presence of abdominal pain
– Presence of weight loss
– Aggravating factors (diet or stress)
– Mitigating factors (alteration of diet, OTC
meds)
– Previous evaluations
History
– Iatrogenic causes (medication history, surgical
history, radiation history)
– Factitious diarrhea (history of eating disorders,
secondary gain and malingering)
– Careful ROS (hyperthyroidism, diabetes
mellitus, CVD, AIDS, etc)
Approach to Patients with
Diarrhea
• Physical Exam
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Presence of rashes or flushing
mouth ulcers
thyroid masses
wheezing
arthritis
anal rectal examination
Erythema Nodosum
Acute Diarrhea
• Less than 2-3 weeks duration
• Majority of cases are mild and self limiting
• 4 million deaths world-wide per year in
children under 5 years
• Categories
– infectious
– noninfectious
• drugs, fecal impaction, elixir diarrhea, enteral
feedings, chemotherapy or radiation therapy,
runner’s diarrhea
Who Needs Evaluation?
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High fever (>102F)
orthostatic symptoms or presyncope
bloody diarrhea
severe abdominal pain
immunocompromised persons
Diagnostic Tests for Acute
Diarrhea
• Spot Stool Sample
– Culture, Ova and Parasite, C.diff toxin, fecal
leukocytes
• Blood Tests
– CBC, electrolytes, SMA 7, blood culture
• Plain X-rays
• Endoscopy
– flex sig
Treatment for Acute Diarrhea
• Symptomatic
– fluid replacement
• Oral replacemet solutions or IV fluids
– antidiarrheals
– Bismuth subsalicylate
• Antimicrobial therapy
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quinolones
metronidazole
Bactrim
Rifaximin
Antidiarrheals and Infectious
Acute Diarrheas
• Bismuth Subsalicylates (Pepto-Bismol)
– safe and efficacious
– antidiarrheal effects, antibacterial,
antiinflammatory
• Loperamide
– safe in traveler’s diarrhea
• Kaolin-pectin, opiates, anticholingerics
– not effective
Antibiotics in Acute Diarrheas
• Recommended
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Shigellosis
Cholera
Traveler’s diarrhea
Pseudomembranous
enterocolitis
– parasites
– STDs
• Not Recommended
– E.coli 0157:H7
Antibiotics
• First Line
– Ciprofloxacin - effective against most enteric
infections
– Metronidazole - if symptoms suggest Giardia
• Second Line
– Bactrim - effective second line therapy for most
infectious diarrheas
Rifaximin (Xifaxan)
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Nonabsorbed
Broad-spectrum antibacterial activity invitro
No known drug interactions
200 mg PO TID or 400 mg PO BID
comparable to cipro
Nosocomial Acute Diarrheas
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Fecal impaction
Drugs
Elixir Diarrhea
Enteral Feedings
Infectious Nosocomial Diarrhea
Chemotherapy/Radiation Therapy
Infectious Nosocomial Diarrheas
• Usually from C.difficile
• Salmonella, Shigella, 0+P extremely rare if
diarrhea develops after 3-4 days in hospital
• In the immunosuppressed, viral infections
are an important cause
Algorithm for Acute Diarrhea
Noninfectious
Infectious
Assess severity, duration
immocompetence of host
Rehydration
and wu
Symptomatic therapy
Continues
Possible abx
antidiarrheal agents
Eval and Rx of
underlying cause
resolves
Chronic Diarrhea
• At least 3 to 4 weeks duration
• accounts for 30% of patients in GI practices
• Categories
– Organic
• malabsorpitive, secretory, exudative (inflammatory)
– Functional
Diagnostic Test for Chronic
Diarrhea
• Blood tests
– CBC, SMA, ESR, Thyroid function
• Stool studies
– Spot
• WBCs, occult blood, O+P, culture, giardia Ag
– Quantitative
• volume/weight, electrolytes, osmolality, fat, pH
• fecal osm gap: 290-2([Na] + [K])
Diagnostic Tests
• Endoscopy
– Flex sig or colonoscopy with biopsies
– Upper endoscopy
• biopsies
• aspiration for bacterial counts and parasites
• Radiology
– Plain Radiographs
– UGI/Small Bowel Series
Malabsorptive Diarrhea
• Fat Malabsorption
– intraluminal maldigestion
– mucosal malabsorption
– postmucosal malabsorption
• intestinal lymphangiectasia, vasuclitis
• Carbohydrate Malabsorption
• Protein Malabsorption (Azotorrhea)
Malabsorptive Diarrheas (Fat)
• Intraluminal Phase
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Cirhosis
Bile duct obstruction
Bacterial overgrowth
Pacreatic exocrine
insufficiencyl
• Mucosal Phase
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Drugs
Infectious disease
Immune system dz
Tropical sprue
Celiac sprue
Whipple’s dz
Abetalipoproteinemia
Celiac Sprue
Normal small bowel
Schilling Test
• Vitamin B 12 deficiency
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Intrinsic factor deficiency
Pancreatic insufficiency
Bacterial overgrowth
Extensive Ileal disease or resection
Schilling Test
1. Ingestion of labeled
Vit B12 and Non- labeled
IM Vit B12
2. Urine labeled
Vit B12 <8%/24 hr=
malabsorption
(Corrects)IF def (PA)
Intrinsic factor
Pancreatic enzymes
Antibiotic therapy
Ileal disease or resection
Panc exoc def
Bact overgrowth
Malabsoprtive Diarrhea (Carbs)
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Sorbitol diarrhea
Fructose diarrhea
Glucose-galactose deficiency
Diasaccharidase deficiency
Lactose/Hydrogen Breath Test
• Step 1 - measure baseline end-expiratory
breath hydrogen levels
• Step 2 - ingestion of lactose 50 gm
• Step 3 - measure breath Hydrogen levels at
30, 60, 90, 120 min
• rise >20 ppm suggest lactose malabsorption
D-Xylose Test
• Step 1 - 25 gm dose of D-xylose ingestion
• Step 2 - urine collected for next 5 hours
• Step 3 - at 1 hour, a blood sample taken
(optional)
• <4gm (16% excretion) in urine or serum
conc <20mg/dl of d-xylose = abnormal
intestinal absorption
Secretory Diarrheas
• Carcinoid Syndrome
• Gastrinoma (ZE syndrome)
• Vipoma or Watery Diarrhea-Hypokalemia
Achlorhydria Syndrome
• Medullary Carcinoma of the Thyroid
• Glucagnoma
• Villous Adenomas
• Systemic Mastocytosis
Inflammatory Diarrheas
• Inflammatory Bowel Disease
• Eosinophilic Gastroenteritis
• Protein-Losing Enteropathy
Inflammatory bowel disease
Crohn’s disease
Granuloma
Treatment for Chronic Diarrhea
• Antidiarrheal therapy
– Mild to Moderate Diarrhea
• Bismuth subsalicylates, opiates, bulk-forming
agents, silicates, anticholingerics, cholestyramine
– Secretory Diarrhea
• octreotide, clonidine, Ca++ channel blockers,
H2blockers, PPIs, H1 blockers, serotonin antagonist,
indomethacin, glucocorticoids