Pseudohyponatremia: Mechanism, Diagnosis, Clinical Associations and Management

Authors

Fahad Aziz, Department of Medicine, Division of Nephrology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA.
Ramin Sam, Department of Medicine, Zuckerberg San Francisco General Hospital, School of Medicine, University of California in San Francisco, San Francisco, CA 94110, USA.
Susie Q. Lew, Department of Medicine, School of Medicine and Health Sciences, George Washington University, Washington, DC 20052, USA.
Larry Massie, Department of Pathology, Raymond G. Murphy Veterans Affairs Medical Center, University of New Mexico School of Medicine, Albuquerque, NM 87108, USA.
Madhukar Misra, Department of Medicine, Division of Nephrology, University of Missouri, Columbia, MO 65211, USA.
Maria-Eleni Roumelioti, Department of Medicine, Division of Nephrology, University of New Mexico School of Medicine, Albuquerque, NM 87106, USA.
Christos P. Argyropoulos, Department of Medicine, Division of Nephrology, University of New Mexico School of Medicine, Albuquerque, NM 87106, USA.
Todd S. Ing, Department of Medicine, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA.
Antonios H. Tzamaloukas, Research Service, Department of Medicine, Raymond G. Murphy Veterans Affairs Medical Center, University of New Mexico School of Medicine, Albuquerque, NM 87108, USA.

Document Type

Journal Article

Publication Date

6-15-2023

Journal

Journal of clinical medicine

Volume

12

Issue

12

DOI

10.3390/jcm12124076

Keywords

dilution effect; electrolyte exclusion effect; hyperviscosity; hyponatremia; pseudohypernatremia; pseudohyponatremia; pseudonormonatremia; serum lipids; serum proteins; serum sodium concentration; serum solids content; serum water sodium concentration

Abstract

Pseudohyponatremia remains a problem for clinical laboratories. In this study, we analyzed the mechanisms, diagnosis, clinical consequences, and conditions associated with pseudohyponatremia, and future developments for its elimination. The two methods involved assess the serum sodium concentration ([Na]) using sodium ion-specific electrodes: (a) a direct ion-specific electrode (ISE), and (b) an indirect ISE. A direct ISE does not require dilution of a sample prior to its measurement, whereas an indirect ISE needs pre-measurement sample dilution. [Na] measurements using an indirect ISE are influenced by abnormal concentrations of serum proteins or lipids. Pseudohyponatremia occurs when the [Na] is measured with an indirect ISE and the serum solid content concentrations are elevated, resulting in reciprocal depressions in serum water and [Na] values. Pseudonormonatremia or pseudohypernatremia are encountered in hypoproteinemic patients who have a decreased plasma solids content. Three mechanisms are responsible for pseudohyponatremia: (a) a reduction in the [Na] due to lower serum water and sodium concentrations, the electrolyte exclusion effect; (b) an increase in the measured sample's water concentration post-dilution to a greater extent when compared to normal serum, lowering the [Na] in this sample; (c) when serum hyperviscosity reduces serum delivery to the device that apportions serum and diluent. Patients with pseudohyponatremia and a normal [Na] do not develop water movement across cell membranes and clinical manifestations of hypotonic hyponatremia. Pseudohyponatremia does not require treatment to address the [Na], making any inadvertent correction treatment potentially detrimental.

APA Citation

Aziz, Fahad; Sam, Ramin; Lew, Susie Q.; Massie, Larry; Misra, Madhukar; Roumelioti, Maria-Eleni; Argyropoulos, Christos P.; Ing, Todd S.; and Tzamaloukas, Antonios H., "Pseudohyponatremia: Mechanism, Diagnosis, Clinical Associations and Management" (2023). GW Authored Works. Paper 2711.
https://hsrc.himmelfarb.gwu.edu/gwhpubs/2711

Department

Medicine