Factitious Diarrhea

Summary

Factitious diarrhea is an intentionally self-inflicted disorder which is motivated either internally by assuming a sick role or externally by money, health benefits, etc. The keys to diagnosis are suspicion and use of readily available stool and urine tests. Since factitious diarrhea is not uncommon and many tests used to evaluate chronic diarrhea are invasive and expensive, it is reasonable to perform a series of basic studies to evaluate for factitious diarrhea early in such an evaluation. Surreptitious laxative use is the most common etiology of factitious diarrhea and can present with volume depletion and an altered biochemical profile. Magnesium-containing laxatives will cause osmotic diarrhea; a high stool osmolar gap and stool magnesium level of more than 90 Meq/L will be present. Stimulant laxatives may cause non-gap diarrhea and can easily be detected in the urine. Any osmolality less than normal (290 mOsmol/kg) indicates dilutional diarrhea, usually the addition of urine or water to stool. All cases of factitious diarrhea should be well documented in the medical record to avoid future unnecessary testing.