|Values are valid only on day of printing.|
It is important to remember that values determined by direct potentiometry-ion selective electrode will be higher in specimens with high protein and lipid concentrations than the corresponding serum specimen that is assayed by an indirect potentiometric method. The whole blood sodium values are the correct values.
Ion selective electrodes are selective but not absolutely specific for the ion in question. Other monovalent cations may react with the electrode but not in the physiologic range.
Tietz Textbook of Clinical Chemistry. Edited by Burtis and Ashwood. Philadelphia, WB Saunders Co, 1994