Chronic DiarrheaChronic Diarrhea

DiarrheaDiarrhea

Loosely defined as passage of abnormally liquid or unformed stools at an increased frequency.

Adults (typical western diet) stool weight > 200g/d

caused by an imbalance in the physiologic mechanisms of the GI tract, resulting in impaired absorption and/or excessive secretion.

2 common conditions (<200 g/d) must be distinguished from diarrhea:

◦Pseudodiarrhea Frequent passage of small volumes of stool Associated with rectal urgency ; accompanies

IBS/proctitis

◦Fecal Incontinence involuntary discharge of rectal contents

most often caused by neuromuscular disorder/structural/anorectal problems

DiarrheaDiarrhea

Type Duration

Acute < 2 weeks

Persistent 2-4 weeks

Chronic > 4 weeks

Chronic DiarrheaChronic Diarrhea

Warrants evaluation to exclude serious underlying pathology

Most of the causes: NON- infectious

Classification by pathophysiological mechanism rational approach to management

Approach to Chronic Approach to Chronic Diarrhea:Diarrhea:Laboratory tools are extensive

costly and invasive rationally directed by a careful History and PE.

When this strategy is unrevealing, simple triage tests (Hx, PE, routine blood studies) are often warranted.◦Characterize the mechanism of diarrhea◦ Identify diagnostically helpful assoc.◦Assess px’s fluid/electrolyte &

nutritional status

HISTORYHISTORY

Family History:

IBD

Sprue

Presence of:

fecal incontinencefeverweight losspain exposure(travel, medications, contacts) common extraintestinal manifestations (skin, arthralgias, oral aphtous ulcers

Diarrhea

Onset

Duration

Pattern

Aggravating and relieving factors (diet)

Characteristics

Physical Findings

Thyroid mass Wheezing Murmurs Edema

Hepatomegaly Abdominal

masses

Lymphadenopathy

Mucocutaneous abnormalities Perianal

fistula Anal sphincter

laxity

Celiac disease

Blood Studies

Peripheral blood leukocytosis↑sedimentation rateC- reactive protein

Anemia

Eosinophilia

Tissue transglutaminase Ab

Inflammation

Blood loss/nutritional

deficiency

Parasites, neoplasia, collagen

vascular disease, allergy,

eosinophilic gastroenteritis

Celiac disease

Chronic DiarrheaChronic Diarrhea2/3 of cases, the causes remain

unclear after the initial encounter further testing is required:◦Quantitative stool collection and

analyses important objective data and establish a diagnosis/characterize the type of diarrhea as a triage for focused additional studies

◦Stool ( >200g/d ) electrolyte concentration, pH, occult blood testing, leukocyte inspection/protein assay, fat quantitation, and laxative screens.

Chronic DiarrheaChronic DiarrheaWhen a specific diagnosis is suggested on the

initial encounter, therapeutic trial is often appropriate, definitive, and highly cost effective. Examples:

◦ Chronic watery diarrhea ceases with fasting in an otherwise healthy young adult may justify a trial of lactose-restricted diet

◦ Bloating w/ diarrhea after a mountain backpacking trip trial of metronidazole (giardiasis)

Any patient with chronic diarrhea + hematochezia evaluated with stool microbiologic studies and colonoscopy

Chronic DiarrheaChronic DiarrheaSecretory diarrheas

◦Microbiologic studies should be done, including: fecal bacterial cultures, inspection for ova and parasites and Giardia antigen assay

◦Suggested history & other findings screening for peptide hormones (gastrin, VIP, calcitonin, TH/TSH, urinary 5-HIAA, and histamine)

◦Upper endoscopy, colonoscopy w/ biopsy and small bowel barium x-rays rule out structural/occult inflammatory disease

Chronic DiarrheaChronic DiarrheaOsmotic diarrhea

◦Tests for 2 most common causes: Lactose intolerance/malabsorption lactose breath

testing or therapeutic trial w/ lactose exclusion & lactose challenge

Magnesium ingestion fecal magnesium levels◦pH low fecal pH suggests CHO malabsorption

Steatorrhea◦Endoscopy w/ small bowel biopsy(includes

aspiration for Giardia and quantitative cultures)◦Small-bowel radiograph◦(-) radiograph/ pancreatic exocrine disease

Pancreatic exocrine insufficiency ruled out secretin-cholecystokinin stimulation test

Chronic DiarrheaChronic DiarrheaChronic inflammatory-type of

diarrheas (presence of blood/leukocytes in the stool)◦Stool cultures◦Inspection for ova/parasites◦C. difficile toxin in assay◦Colonoscopy w/ biopsies◦Small-bowel contrast studies