Chronic Diarrhea

last authored: Oct 2009, Dave LaPierre

 

Introduction

Chronic diarrhea is defined as persistent loose, frequent stools, lasting longer than 2-3 weeks. This is in contrast to acute diarrhea. Amount is normally greater than 300g/day in adults, >200g/day in children, and >10g/kg/day in infants. Functional disorders need to persist over 3 months to make a diagnosis.

 

The Case of...

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Differential Diagnosis

Causes of acute diarrhea can also become chronic.

Most common causes

Other causes:

  • allergies (ie milk protein)
  • diabetes
  • short gut syndrome
  • antibiotics
  • laxatives
  • chemotherapeutics agents

metabolic/endocrine/genetic causes

  • hyperhyroidism
  • Addison's disease
  • galactosemia
  • carbohydrate malabsorption
  • fat malabsorption
  • protein-losing eneteropathy
  • Scwachman-Diamond syndrome

 

dietary

  • mannitol, sorbitol
  • overfeeding, especially fibre
  • Toddler's diarrhea: excess juice
  • fructose intolerance

Common infections/infestations

bacteria

parasites

viruses

 

immune

  • IgA deficiency
  • hypogammaglobulinemia
  • SCID
  • AIDS

 

neoplastic

  • phaeochromocytoma
  • small bowel lymphoma
  • carcinoid tumours
  • secretory tumours

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History and Physical Exam

  • history
  • physical exam

History

  • onset, duration, and pattern of stool
  • stool quality and characteristics (colour, odor, consistency, blood, mucus, undigested food)
  • aggrevating or alleviating factors
  • fever and other constitutional symptoms
  • weight loss (eliminates lactose, functional as causes)
  • vomiting (seen in celiac disease, infection)

past medical history

  • gastroenteritis
  • constipation
  • recurrent penumonia
  • diabetes
  • hyperthyroidism
  • IBS
  • lactose intolerance
  • bowel surgery
  • scleroderma

dietary history (4 F's)

  • fibre
  • fluid
  • fat
  • fruit juice

medications

  • antibiotics
  • laxatives

social history

  • recent travel
  • other exposures to pathogens

 

Areas to query, with indications towards a small or large intestine cause, are as follows:

symptom

small intestine

large intestine

volume

frequency

blood

pain

rectal symptoms

steatorrhea

weight loss

effect of fasting

nutritional deficiencies

+++

+

-

absent/periumbilical

-

+

++

decrease

++

+

+++

+

lower quadrant

+

-

+/-

no change

+/-

 

Physical Exam

Obtain body weight and height, especially in infants and children, and plot on growth chart. If child is well and thriving, little further investigations are required.

 

HEENT

  • conjunctival pallor

extremeties and skin

  • clubbing
  • edema
  • jaundice
  • pallor
  • eczematous rash
  • bruising

respiratory (why - CF?)

  • wheezing
  • crackles

abdomen

  • tenderness
  • masses (stool, abscess, tumour, organomegaly)
  • rectum: perianal disease, prolapse, Hirschpruing disease, constipation

vitamin deficiency

  • A: vision difficulties
  • D: osteoporosis, fractures
  • E: neuropathy
  • K: bruising

 

Perform a rectal examination and test for occult blood.

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Investigations

Given the extensive differential diagnosis, specialist referral is important if no immediate causes are identified.

  • lab investigations
  • diagnostic imaging

Lab Investigations

Investigations should be guided by suspected diagnoses.

 

blood tests

  • CBCD
  • electrolytes
  • BUN, creatinine
  • ALT, AST, AP, GGT, bili, INR
  • calcium, magnesium, phosphorus
  • ferritin, B12, RBC folate, albumin, prealbumin, INR to assess malabsorption
  • TSH
  • anti TTG
  • endomysial antibody

stool

  • occult blood
  • osmotic gap: 280 - (Na + K)x2
  • If it is less than 50, it is secretory. If it is over 50, it is osmotic.
  • leukocytes (present in stool only if lower GI source)

microbiology

  • Stool for O and P, C and S
  • viruses
  • C diff toxin A+B
  • Giardia toxin

 other

  • 24 hour stool for weight and electrolytes (difficult to complete)
  • 72 hour stool for fat; if steatorrhea, consider pancreatic investigations
  • pH and reducing sugars: can be seen in carbohydrate malabsorption, ie lactose intolerance
  • stool can be tested for phenothalin to investigate laxative abuse
  • sweat test can be done for cystic fibrosis

Low stool osmolality means people are adding water to their stool to fake symptoms.

Diagnostic Imaging

Colonoscopy for large bowel diarrhea.

CT abdomen

Small bowel biopsy or follow-through studies.

Large-bowel biopsy

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Management

Emperic treatment while waiting for diagnosis includes dietary restriction, increased dietary or supplemental fibre, or cholestyramine. As cause becomes evident, treatment should be instituted accordingly.

If patients are severely malnourished, restarting nutrition can result in refeeding syndrome. Electrolytes need to be corrected and monitored as food is gradually reintroduced.

Additional supplements may be required over the short- or long-term.

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Pathophysiology

This section needs to be cleaned up quite a bit..!

 

An osmotic diarrhea will decrease with decreased intake, while secretory diarrhea will not.

 

Osmotic

Increased transit (IBS)

maldigestion. infections can result in lactase deficiency, and people should remain on a lactose-free diet for several days to exclude this possibility.

mucosal damage

short gut

secretory

 

inflammatory

inflammatory bowel disease

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The Case of...

 

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Additional Resources

 

 

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Topic Development

created: DLP, Aug 09

authors: DLP, Aug 09

editors:

reviewers:

 

 

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