Where Do the Salt and Water Go? A Case of Profound Hyponatremia

Department

Medicine

Document Type

Article

Publication Title

American Journal Of Kidney Diseases

Abstract

Treatment of profound hyponatremia is challenging. Severe symptoms mandate correction by 4 to 6 mEq/L within hours, but with risk factors for osmotic demyelination, daily correction should be < 8 mEq/L. With a therapeutic window this narrow, clinicians would like to know how serum sodium (SNa) concentration will respond to their therapy. Based on isotopic measurements, Edelman showed SNa level to be a function of exchangeable sodium and potassium divided by total-body water. Edelman defined this relationship with linear regression yielding an equation of the form y = mx + b, where y is SNa level, x is exchangeable sodium and potassium divided by total-body water, m is the slope, and b is the intercept. Edelman said that the intercept of his regression "probably is a measure of the quantity of osmotically inactive exchangeable sodium and potassium per unit of body water." Predictive formulas are derived from Edelman's original linear regression, some including and some omitting the regression's intercept. We illustrate the performance and limitations of these formulas using comprehensive data for electrolyte and fluid balance obtained during the treatment of a critically patient who presented with an SNa concentration of 101 mEq/L.

First Page

885

Last Page

889

DOI

10.1053/j.ajkd.2018.07.011

Volume

72

Issue

6

Publication Date

12-1-2018

Medical Subject Headings

Alcoholism (complications, diagnosis); Body Water (metabolism); Combined Modality Therapy (methods); Emergency Service, Hospital; Follow-Up Studies; Humans; Hyponatremia (etiology, physiopathology, therapy); Linear Models; Male; Middle Aged; Predictive Value of Tests; Risk Assessment; Severity of Illness Index; Sodium (blood); Sodium Chloride (administration & dosage); Treatment Outcome; Water-Electrolyte Imbalance (diagnosis, therapy)

PubMed ID

30266221

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