Formulas for fixing serum sodium: curb your enthusiasm
Related Experiment Video
Updated: Mar 17, 2026

Studying the Activity of Neuropeptides and Other Regulators of the Excretory System in the Adult Mosquito
Published on: August 24, 2021
1University of Rochester School of Medicine and Dentistry, Rochester General Hospital , 1425 Portland Avenue, Rochester, NY 14534 , USA.
Abstract:
A variety of formulas have been proposed to predict changes in serum sodium concentration. All are based on an experiment done over 50 years ago by Edelman, who derived a formula relating the plasma sodium concentration to isotopically measured body sodium, potassium, and water. Some of these formulas fail because they do not include urinary losses of electrolytes and water. Even those that include these essential variables are not accurate enough for clinical use because it is impractical to adjust calculations to rapid changes in urinary composition, and because the formulas do not account for changes in serum sodium caused by internal exchanges between soluble and bound sodium stores or shifts of water into or out of cells resulting from changes in intracellular organic osmolytes. Nephrologists should curb their enthusiasm for predictive formulas and rely instead on frequent measurements of the serum sodium when correcting hyponatremia and hypernatremia.
Related Concept Videos
Calculating pH Changes in a Buffer Solution
Serum Studies: Renal Function Tests
Regulation of Sodium and Potassium
Sodium Regulation
Sodium ions make up approximately 90% of extracellular cations, with a normal blood plasma concentration of 136–148 mEq/L. A decrease in blood volume and pressure triggers the release of renin from granular cells in the juxtaglomerular complex (JGC), primarily...
Determining the pH of Salt Solutions
Drug Dosing in Renal Diseases: Estimation of Glomerular Filtration Rate Based on Serum Creatinine Concentration
Drug Dosing in Renal Diseases: Dose Adjustments Based on Drug Clearance and Elimination Rate Constant

