title: A new formula for predicting alterations in plasma sodium concentration in peritoneal dialysis.
abstract: Alterations in the plasma water sodium concentration ([Na+]pw) result from changes in the total exchangeable sodium (Na e), total exchangeable potassium (K e), and total body water (TBW). The empirical relationship between the [Na+]pw and Na e, K e, and TBW was originally demonstrated (Edelman IS, Leibman J, O'Meara MP, and Birkenfeld LW. J Clin Invest 37: 1236-1256, 1958), where [Na+]pw = 1.11(Na e + K e)/TBW - 25.6 (Eq. 1). Based on Eq. 1, alterations in the [Na+]pw can be predicted by considering changes in the mass balance of Na+, K+, and H2O. In accounting for the mass balance of Na+, K+, and H2O in patients on peritoneal dialysis, considerations must also be taken to determine the modulating effect of dialysate clearance of Na+ and K+ and fluid changes resulting from this therapeutic modality on the [Na+]pw. In this article, we derive a new formula for predicting alterations in the plasma Na+ concentration ([Na+]p) in patients on peritoneal dialysis, taking into consideration the empirical relationship between the [Na+]pw and Na e, K e, and TBW (Eq. 1) as well as changes in mass balance of Na+ + K+ and H2O.
authors.affiliation: Div. of Nephrology, David Geffen School of Medicine at UCLA, Rm. 7-155 Factor Bldg., 10833 Le Conte Ave., 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; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000628:therapy*; D008954:Models, Biological; D010530:Peritoneal Dialysis; D011188:Potassium / Q000378:metabolism; D011237:Predictive Value of Tests; D012964:Sodium / Q000097:blood*; D014867:Water / Q000378:metabolism; D014882:Water-Electrolyte Balance / Q000502:physiology
chemical_list: D014867:Water; D012964:Sodium; D011188:Potassium