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...
Differential Diagnosis
Causes of acute diarrhea can also become chronic.
Most common causes
Other causes:
metabolic/endocrine/genetic causes
dietary
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Common infections/infestationsbacteria
parasites
viruses
immune
neoplastic
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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.
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
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.
- dietitians are critical in managing malabsorption, celiac disease, or allergic enteropathy
- oral rehydration can be given if vomiting is not present
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.
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
- lactose intolerance
- celiac disease
- short gut syndrome
- cystic fibrosis
- Crohn's disease
secretory
- cholera
inflammatory
inflammatory bowel disease
The Case of...
Additional Resources
Topic Development
created: DLP, Aug 09
authors: DLP, Aug 09
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reviewers:
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