Medical calculator
Stool Osmotic Gap
Estimates the stool osmotic gap from stool sodium, stool potassium, and stool osmolality to help distinguish osmotic from secretory diarrhea.
Enter stool sodium concentration, stool potassium concentration, and stool osmolality, then calculate.
Stool chemistry inputs
The source page lists typical stool chemistry values as sodium 30 mEq/L, potassium 75 mEq/L, and osmolarity 290 to 300 mOsm/kg.
Stool sodium
Use the measured stool sodium concentration.
Stool potassium
Use the measured stool potassium concentration.
Stool osmolarity
Use the measured stool osmolarity or osmolality value.
mOsm/kg