digest
Short Summary
Main recommendation: For chronic diarrhea, follow a stepwise workup, starting with history, exam, and a limited screening panel, and consider IBS-D only after alarm features and other abnormalities are excluded, while watching for overlapping conditions in patients whose history does not fit cleanly. The case presented is a 21-year-old woman whose new symptoms, including postural tachycardia, flushing, urticaria, and a mildly elevated serum tryptase, are clues the presenter says may suggest overlapping conditions beyond IBS-D.
Key Points
- Chronic diarrhea is defined as recurrent loose, watery stools lasting more than four weeks.
- The initial evaluation includes a thorough medical, dietary, medication, and psychosocial history, a physical exam with digital rectal exam to check for incontinence, and a search for alarm features that trigger patient-specific testing.
- Without alarm features, the guideline-recommended limited screen is CBC, CMP, fecal calprotectin, CRP, tissue transglutaminase IgA, Giardia testing, and bile acid diarrhea testing.
- Abdominal pain associated with defecation, plus Rome criteria, supports IBS-D; without pain, a provisional diagnosis of functional diarrhea is considered.
- Based on the standard algorithm, the patient would be diagnosed with IBS-D, but the presenter notes certain clues in her history may suggest overlapping or mimicking conditions, which Dr. Harris will address next.
Details Worth Noting
- Concrete instructions:
- Take a full medical, dietary, medication, and psychosocial history and perform a physical exam including a digital rectal exam.
- If alarm features are present, pursue patient-specific investigation and treat any abnormality found.
- If no alarm features are present, order CBC, CMP, fecal calprotectin, CRP, tissue transglutaminase IgA antibody, Giardia testing, and bile acid diarrhea testing.
- If bile acid diarrhea is suspected but testing is unavailable (as in North America), the AGA suggests it is reasonable to empirically treat with bile acid binders.
- If no abnormalities are found, assess for abdominal pain with defecation and apply the Rome criteria for IBS-D.
- For a provisional functional diarrhea diagnosis, give reassurance, education, lifestyle and dietary advice, and empiric therapy, then assess for improvement; if no improvement, consider colonoscopy with biopsy to rule out microscopic colitis.
- The Rome IV functional diarrhea criteria are loose or watery stools without predominant abdominal pain or discomfort, bloating more than 25 percent of the time, not meeting IBS-D criteria, symptoms for at least three months, and onset at least six months before diagnosis.
- In the case, the patient's labs were mostly normal, but serum tryptase was mildly elevated at 15.9.
- Her exam showed heart rate rising from 70 supine to 105 standing, blood pressure falling from 99/64 to 91/58, flushing, a positive wheal on scratch testing, and a Beighton score of 6 of 9.
- Her history includes a gastroenteritis episode on a cruise followed by near-syncope, palpitations, brain fog, and fatigue, and symptoms worsen with stress and alcohol.
Bottom Line
The case shows that chronic diarrhea with flushing, urticaria, and orthostatic changes should prompt a broader search beyond IBS-D, since the presenter explicitly suggests overlapping conditions may be present.
