title: Lower plasma sodium is associated with a microinflammatory state among patients with advanced chronic kidney disease.
abstract: OBJECTIVE
  Lower serum sodium levels have been associated with increased mortality among patients with chronic kidney disease (CKD). Our aim was to analyze the independent factors associated with lower sodium levels among nondialysis patients with advanced CKD and to evaluate the evolution of these patients in comparison to those with higher plasma sodium over a 1-year period.
  
  
  METHODS
  We included 72 patients with CKD stages 4 and 5 without clinically evident cardiopathy or liver disease. Bioelectrical impedance and echocardiography were performed to analyze the possible relation between plasma sodium and volume status and subclinical left ventricular (LV) dysfunction. During follow-up, we compared the evolution of patients with lower baseline plasma sodium (low quartile: <138 mEq/l) with that of patients with higher levels over a 1-year period.
  
  
  RESULTS
  At baseline, the independent predictors of lower plasma sodium were C-reactive protein (CRP; OR 0.96; 95% CI 0.91-0.99) and body mass index (OR 0.89; 95% CI 0.78-0.99). An inverse correlation between plasma sodium and CRP was observed (r = -0.32; p = 0.01). Plasma sodium did not correlate with extracellular water and was not different between patients with or without echocardiographic data of LV dysfunction (p = 0.7). During follow-up, patients with lower sodium at baseline showed persistently lower sodium values (p = 0.04), higher CRP (p = 0.05), lower serum albumin (p < 0.01) and higher erythropoietin-stimulating agent resistance index (p = 0.05).
  
  
  CONCLUSIONS
  Our results suggest an association between lower plasma sodium and a microinflammatory state among patients with advanced CKD. Inflammation could be an underlying confounding factor explaining the increased mortality in these patients.
authors.affiliation: Hospital Severo Ochoa, Leganés, Spain.
authors.forename: Olimpia
authors.initials: O
authors.lastname: Ortega
authors.forename: Gabriela
authors.initials: G
authors.lastname: Cobo
authors.forename: Isabel
authors.initials: I
authors.lastname: Rodríguez
authors.forename: Rosa
authors.initials: R
authors.lastname: Camacho
authors.forename: Paloma
authors.initials: P
authors.lastname: Gallar
authors.forename: Carmen
authors.initials: C
authors.lastname: Mon
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Herrero
authors.forename: Milagros
authors.initials: M
authors.lastname: Ortiz
authors.forename: Aniana
authors.initials: A
authors.lastname: Oliet
authors.forename: Cristina
authors.initials: C
authors.lastname: Di Gioia
authors.forename: Ana
authors.initials: A
authors.lastname: Vigil
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000032:analysis; D004452:Echocardiography; D017097:Electric Impedance; D005260:Female; D006801:Humans; D007249:Inflammation / Q000097:blood; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000401:mortality; D008297:Male; D011446:Prospective Studies; D012307:Risk Factors; D012709:Serum Albumin / Q000032:analysis; D012964:Sodium / Q000097:blood*; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis / Q000503:physiopathology
chemical_list: D015415:Biomarkers; D012709:Serum Albumin; D002097:C-Reactive Protein; D012964:Sodium