Measurement of the faecal osmotic gap may help differentiate between secretory and osmotic diarrhoea. The following results were obtained on a faecal sample:
ā Osmolality: 280 mOsm/kg
ā Faecal sodium: 20 mmol/L
ā Faecal potassium: 65 mmol/L
What is the faecal osmotic gap?
1
. 40 mOsm/kg
2
110 mOsm/kg
3
130 mOsm/kg
4
Ā 175 mOsm/kg