Q: How to rule out Osmotic Diarrhea in ICU?
Answer: The easiest way to rule out osmotic diarrhea is via calculating simple formula of Osmotic gap
290-2 x (stool Na + Stool K)
Gap more than 100 mOsm/kg, is probably an osmotic diarrhea.
Gap less than 50mOsm/Kg rules out osmotic diarrhea.
Gap between 50 and 100 mOsm/kg is equivocal
In ICU most usual causes of osmoticc diarrhea are medications (containing nonabsorbable sugar alcohols like Sorbitol) and tube feeds.
Further reading: - Here -Mechanisms, prevention, and management of diarrhea in enteral nutrition - Kevin Whelan and Ste´phane M. Schneider - Current Opinion in Gastroenterology 2011, 27:152–159