Diarrhea
Definition
• Increased liquidity, frequency or decreased consistency of stools
Mechanisms
• 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– gluc-galact malab
– fructose malab
– disaccaridase def
– ingestion (poorly absorbable carbs)
• 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– 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– 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?
• 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– 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– 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)
• 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
• 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
Infectious
Assess severity, durationimmocompetence of host
Noninfectious
Eval and Rx of underlying cause
Symptomatic therapy
Continues
Rehydrationand wu
Possible abxantidiarrheal agents
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– Cirhosis
– Bile duct obstruction
– Bacterial overgrowth
– Pacreatic exocrine insufficiencyl
• Mucosal Phase– 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– 1. Intrinsic factor deficiency– 2. Pancreatic insufficiency– 3. Bacterial overgrowth– 4. Extensive Ileal disease or resection
Schilling Test1. Ingestion of labeledVit B12 and Non- labeledIM Vit B12
2. Urine labeledVit B12 <8%/24 hr=malabsorption
Intrinsic factor
Pancreatic enzymes
Antibiotic therapy
Ileal disease or resection
IF def (PA)
Panc exoc def
Bact overgrowth
(Corrects)
Malabsoprtive Diarrhea (Carbs)
• 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
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