What is Stool osmotic gap ?
It is a calculation performed to distinguish among different causes of diarrhea.
What will be the Cause of Normal/Low & high Osmotic Gap?
A low stool osmolic gap can imply secretory diarrhea, while a high gap can imply osmotic diarrhea.
How it is Calculated ?
It is calculated with the equation 290 − 2 * (stool Na + stool K). The 290 is the value of the stool osmolality. The stool osmolality is usually not directly measured, and is often given a constant in the range of 290 to 300.
What are the causes of Osmotic Diarrhea ?
High osmotic gap (>100 mosm/kg):