Why should Na+ levels be measured only in the aqueous phase?

Updated: Aug 16, 2019
  • Author: Christie P Thomas, MBBS, FRCP, FASN, FAHA; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

The newer method (using ion-specific Na+ electrodes) measures the Na+ in the aqueous phase only, thus avoiding the error of pseudohyponatremia. Pseudohyponatremia should be suspected when the measured plasma osmolality is normal in the presence of hyponatremia. Pseudohyponatremia may continue to be a problem in parts of the world where flame photometry is still used to measure Na+.


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