Intra-erythrocytic sodium in uremic patients, as determined by "high-resolution" 23Na nuclear magnetic resonance.

The use of 23Na nuclear magnetic resonance with aqueous shift reagent has made it possible to determine intracellular sodium concentrations in living erythrocytes. We applied this technique to samples from 16 healthy subjects and 41 uremic patients. The results seem to show distinct populations among the latter. Classically, two different relaxation times are obtained for intracellular sodium in biological media, according to relaxation NMR theory. Some patients, however, exhibit abnormal results that cannot be accounted for by this theory.