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Clin Exp Nephrol. 2004 Jun;8(2):98-102.

Role of potassium in hypokalemia-induced hyponatremia: lessons learned from the Edelman equation.

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Division of Nephrology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Room 7-155 Factor Building, Los Angeles, CA 90095, USA.


It is well known that changes in the mass balance of K+ can lead to an alteration in the plasma water sodium concentration ([Na+]pw). We have recently shown that based on the Edelman equation, the [Na+]pw is determined by the total exchangeable Na+ (Nae), total exchangeable K+ (Ke), total body water (TBW), osmotically inactive Nae and Ke, plasma water [K+], intracellular and extracellular osmotically active non-Na+ and non-K+ osmoles, and plasma osmotically active non-Na+ and non-K+ osmoles. In light of these findings, a re-analysis of the role of K+ in modulating the [Na+]pw is required in understanding the pathophysiology of hypokalemia-induced hyponatremia. In this article, we characterize the complex role of K+ in the pathogenesis of hypokalemia-induced hyponatremia using a three-compartment model and the known parameters in the Edelman equation. Our analysis indicates that K+ modulates the [Na+]pw by changing Ke in addition to the parameters in the y-intercept of the Edelman equation. Moreover, the magnitude of potassium-induced changes in the [Na+]pw is determined by the pathophysiologic mechanisms by which changes in Ke occur.

[Indexed for MEDLINE]

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