Absorption of sodium from hypertonic sodium phosphate enema solutions

Absorption of sodium from hypertonic sodium phosphate enema solutions has been studied in 11 patients by means of labeling the contained sodium with added 24Na and determining the radioactivity of body fluids after administration of the enemas. The sodium absorption thus estimated is a maximal figure and may represent an overestimate, since radioactivity can enter the body fluids by ion exchange without net transport of sodium. An average of 5.5 per cent of the instilled radioactivity was absorbed, corresponding to not more than 228 mg sodium. Absorption of such a quantity of sodium does not appear to represent a source of concern in the management of salt-restricted patients.