Sodium faeces

Specimen:

5 g liquid faeces. The test is of no value if faeces are solid.

Method:

ISE, flame photometry.

Reference Interval:

< 45 mmol/L.

Application:

Differentiation of secretory from non-secretory diarrhoea.

Interpretation:

Secretory diarrhoea (pancreatic islet cell tumour, cathartics, enterotoxins eg, cholera) results in liquid faeces with high sodium levels, typically 55-100 mmol/L.

Reference:

Shiau Y-F et al. Ann Int Med 1985; 102: 773-775.