AD 11/02
Chronic Diarrhea
When and how to evaluate for chronic diarrhea?
! Patients with > 4 weeks of diarrhea should be evaluated for chronic diarrhea. After 4
weeks, most acute infectious enteritides will have resolved.
! Take a good history and physical. Ask about duration, frequency, blood, travel history,
relation of food to diarrhea, medications, other systemic symptoms.
! Consider these broad categories: malabsorptive, secretory, inflammatory, motility,
infectious.
! The proposed stepwise evaluation has two outpatient stages, followed by a third inpatient
stage if necessary (i.e. not necessary to send lots of elaborate tests right away). Authors
state that this approach leads to a diagnosis in 90% of cases.
Preliminary workup:
•Confirm that patient truly has diarrhea: more than 300 gm stool weight in 24 hours.
•Prescribe a lactose-free diet for several days to rule out secondary lactase deficiency, which is
common after an acute episode of diarrhea.
•Test for HIV in the appropriate clinical setting (this article applies to non-HIV infected cases).
•Correct dehydration while the workup is proceeding.
Stage one - outpatient evaluation
•History and limited labs to identify common causes of chronic diarrhea. The following work-up
should be tailored to the individual.
Lactose free diet supervised by nutritionist: to rule out lactase deficiency.
Fecal wbc (inflammatory), stool O&P, C. dif toxin.
Common infectious causes include:
giardia: upper abdominal cramps, “frothy” stool. Sensitivity of O&P x 3 is 60-85%.
amebiasis: watery or bloody stool, +/- fecal WBCs. Sensitivity of O&P x 3 is 60-90%.
Stool pH: carbohydrate intolerance (due to viral enteritis with small intestinal mucosal
damage, or due to antibiotics, which alter gut flora) causes bloating, flatus, cramping.
Stool pH <5.3 is diagnostic.
24 hr fecal fat: must be performed with patient on strict diet of 75-100 gm/24 hrs. Normal
excretion is <7 gm fat/24 hrs. Historical clues of ste