written by David LaPierre, last reviewed April 2009
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.
Causes of acute diarrhea can also become chronic.
Most common causes
Other causes:
metabolic/genetic causes
dietary
|
Common infections/infestationsbacteria
parasites
viruses
|
Given the extensive differential diagnosis, specialist referral is important if no immediate causes are identified.
past medical history
dietary history (4 F's)
medications
social history
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 +/- |
Obtain body weight and height, especially in infants and children, and plot on growth chart.
HEENT
extremeties and skin
respiratory (why - CF?)
abdomen
vitamin deficiency
Perform a rectal examination and test for occult blood.
blood tests
stool
microbiology
other
Low stool osmolality means people are adding water to their stool to fake symptoms.
Colonoscopy for large bowel diarrhea.
CT abdomen
Small bowel biopsy or follow-through studies.
Large-bowel biopsy -
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.
This section needs to be cleaned up quite a bit..!
An osmotic diarrhea will decrease with decreased intake, while secretory diarrhea will not.
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
inflammatory bowel disease