title: Body sodium, potassium and water in peritoneal dialysis-associated hyponatremia.
abstract: OBJECTIVE
  This report presents a method quantitatively analyzing abnormalities of body water and monovalent cations (sodium plus potassium) in patients on peritoneal dialysis (PD) with true hyponatremia.
  
  
  METHODS
  It is well known that in the face of euglycemia serum sodium concentration is determined by the ratio between the sum of total body sodium plus total body potassium on the one hand and total body water on the other. We developed balance equations that enabled us to calculate excesses or deficits, relative to the state of eunatremia and dry weight, in terms of volumes of water and volumes of isotonic solutions of sodium plus potassium when patients presented with hyponatremia. We applied this method retrospectively to 5 episodes of PD-associated hyponatremia (serum sodium concentration 121-130 mEq/L) and compared the findings of the method with those of the clinical evaluation of these episodes.
  
  
  RESULTS
  Estimates of the new method and findings of the clinical evaluation were in agreement in 4 of the 5 episodes, representing euvolemic hyponatremia (normal total body sodium plus potassium along with water excess) in 1 patient, hypovolemic hyponatremia (deficit of total body sodium plus potassium along with deficit of total body water) in 2 patients, and hypervolemic hyponatremia (excess of total body sodium along with larger excess of total body water) in 1 patient. In the 5(th) patient, in whom the new method suggested the presence of water excess and a relatively small deficit of monovalent cations, the clinical evaluation had failed to detect the cation deficit.
  
  
  CONCLUSIONS
  Evaluation of imbalances in body water and monovalent cations in PD-associated hyponatremia by the method presented in this report agrees with the clinical evaluation in most instances and could be used as a guide to the treatment of hyponatremia. Prospective studies are needed to test the potential clinical applications of this method.
authors.affiliation: Raymond G. Murphy VA Medical Center, Albuquerque, New Mexico, USA; University of New Mexico School of Medicine, Albuquerque, New Mexico, USA; Department of Medicine, Loyola University Chicago, Maywood, Illinois, USA; and Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USARaymond G. Murphy VA Medical Center, Albuquerque, New Mexico, USA; University of New Mexico School of Medicine, Albuquerque, New Mexico, USA; Department of Medicine, Loyola University Chicago, Maywood, Illinois, USA; and Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA.
authors.forename: Yijuan
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Raymond G. Murphy VA Medical Center, Albuquerque, New Mexico, USA; University of New Mexico School of Medicine, Albuquerque, New Mexico, USA; Department of Medicine, Loyola University Chicago, Maywood, Illinois, USA; and Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA.
authors.forename: David
authors.initials: D
authors.lastname: Mills
authors.affiliation: Raymond G. Murphy VA Medical Center, Albuquerque, New Mexico, USA; University of New Mexico School of Medicine, Albuquerque, New Mexico, USA; Department of Medicine, Loyola University Chicago, Maywood, Illinois, USA; and Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA.
authors.forename: Todd S
authors.initials: TS
authors.lastname: Ing
authors.affiliation: Raymond G. Murphy VA Medical Center, Albuquerque, New Mexico, USA; University of New Mexico School of Medicine, Albuquerque, New Mexico, USA; Department of Medicine, Loyola University Chicago, Maywood, Illinois, USA; and Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA.
authors.forename: Joseph I
authors.initials: JI
authors.lastname: Shapiro
authors.affiliation: Raymond G. Murphy VA Medical Center, Albuquerque, New Mexico, USA; University of New Mexico School of Medicine, Albuquerque, New Mexico, USA; Department of Medicine, Loyola University Chicago, Maywood, Illinois, USA; and Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USARaymond G. Murphy VA Medical Center, Albuquerque, New Mexico, USA; University of New Mexico School of Medicine, Albuquerque, New Mexico, USA; Department of Medicine, Loyola University Chicago, Maywood, Illinois, USA; and Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA.
authors.forename: Antonios H
authors.initials: AH
authors.lastname: Tzamaloukas
mesh_terms: D000328:Adult; D000368:Aged; D001826:Body Fluids / Q000737:chemistry*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007010:Hyponatremia / Q000209:etiology / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010530:Peritoneal Dialysis / Q000009:adverse effects*; D011188:Potassium / Q000378:metabolism*; D011446:Prospective Studies; D012964:Sodium / Q000378:metabolism*; D014867:Water / Q000378:metabolism*; D014883:Water-Electrolyte Imbalance / Q000150:complications* / Q000378:metabolism; D055815:Young Adult
chemical_list: D014867:Water; D012964:Sodium; D011188:Potassium
keywords: Hyponatremia; euvolemia; hypervolemia; hypovolemia; potassium balance; sodium balance; water balance