title: Hyponatraemia, mortality and haemodialysis: An unexplained association.
abstract: BACKGROUND
  As in the general population, in patients on haemodialysis (HD) hyponatraemia is associated with higher mortality risk. The objective of this article was to study the relationship between predialysis serum sodium (sNa) and mortality in an HD population. We also intended to define hyponatraemia and determine the characteristics of hyponatraemic patients in terms of anthropometric data, analytical features, dialysis measurements and hydration (bioimpedance).
  
  
  METHODS
  Observational, descriptive study of a cohort of HD incident patients. The independent variable was the mean of each patient's sNa analysed during their first 6 months on HD.
  
  
  RESULTS
  A total of 4,153 patients were included in the study. Mean age was 64.7 years; 65.2% of the patients were male and 35% were diabetics. Mean follow-up time was 21.48 (SD) (1.31) months. sNa had a normal distribution, with a mean (SD)=138.46 (2.7) mEq/l. Body weight, diabetes mellitus, systolic blood pressure, interdialytic weight gain, total ultrafiltration, serum glucose, albumin and creatinine, vascular access and haemodialysis type, acquire significant differences between sodium quartiles. Lean tissue index (LTI) in patients with low serum sodium, Q1 (135 mEq/l), was significantly lower than the LTI of patients from the other serum sodium quartiles. Patients with sNa<136 mEq/l had a higher independent mortality risk (OR=1.62) (Cox regression analysis).
  
  
  CONCLUSIONS
  HD patients with hyponatraemia patients have a poor prognosis and present malnutrition or fluid overload.
authors.affiliation: Servicio de Nefrología, Hospital Universitario Infanta Leonor, Madrid, España. Electronic address: rperezga@salud.madrid.org.
authors.forename: Rafael
authors.initials: R
authors.lastname: Pérez-García
authors.affiliation: NephroCare Medical Management, Fresenius Medical Care, Madrid, España.
authors.forename: Inés
authors.initials: I
authors.lastname: Palomares
authors.affiliation: NephroCare Medical Management, Fresenius Medical Care, Madrid, España.
authors.forename: José Ignacio
authors.initials: JI
authors.lastname: Merello
authors.affiliation: NephroCare Medical Management, Fresenius Medical Care, Madrid, España.
authors.forename: Rosa
authors.initials: R
authors.lastname: Ramos
authors.affiliation: Departamento de Nefrología y Trasplante Renal, Hospital Clinic, Universidad de Barcelona, Barcelona, España.
authors.forename: Francisco
authors.initials: F
authors.lastname: Maduell
authors.affiliation: Servicio de Nefrología, Hospital Universitario Santa Lucía, Cartagena (Murcia), España.
authors.forename: Manolo
authors.initials: M
authors.lastname: Molina
authors.affiliation: Departamento de Nefrología, Hospital Universitario Reina Sofía, Córdoba, España.
authors.forename: Pedro
authors.initials: P
authors.lastname: Aljama
authors.affiliation: NephroCare Coordination, Fresenius Medical Care, Bad Homburg, Alemania.
authors.forename: Daniele
authors.initials: D
authors.lastname: Marcelli
mesh_terms: D000368:Aged; D015331:Cohort Studies; D003404:Creatinine; D003920:Diabetes Mellitus; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000401:mortality*; D007676:Kidney Failure, Chronic; D008297:Male; D011379:Prognosis; D006435:Renal Dialysis / Q000401:mortality*; D012964:Sodium
chemical_list: D012964:Sodium; D003404:Creatinine
keywords: Diabetes; Haemodialysis; Hemodiálisis; Hiponatremia; Hyponatraemia; Mortalidad; Mortality; Natremia; Serum sodium