title: Role of potassium in hypokalemia-induced hyponatremia: lessons learned from the Edelman equation.
abstract: 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.
authors.affiliation: Division of Nephrology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Room 7-155 Factor Building, Los Angeles, CA 90095, USA. mtnguyen@mednet.ucla.edu
authors.forename: Minhtri K
authors.initials: MK
authors.lastname: Nguyen
authors.forename: Ira
authors.initials: I
authors.lastname: Kurtz
mesh_terms: D006801:Humans; D007008:Hypokalemia / Q000378:metabolism*; D007010:Hyponatremia / Q000378:metabolism*; D007674:Kidney Diseases / Q000378:metabolism*; D008954:Models, Biological; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D014867:Water / Q000378:metabolism; D014883:Water-Electrolyte Imbalance / Q000378:metabolism
chemical_list: D014867:Water; D012964:Sodium; D011188:Potassium