title: Characteristics and clinical outcomes of hyponatraemia in peritoneal dialysis patients.
abstract: OBJECTIVE
  There are few reports on the incidence, aetiology, and mortality of peritoneal dialysis (PD) patients with hyponatraemia.
  
  
  METHODS
  We identified all adults (>18-years-of-age) who received PD between May 2001 and March 2010. The patients were divided into two groups according to the presence of hyponatraemia (<135 mmol/L) during follow-up. Total body water (TBW) was obtained from bioimpedance analysis. Appropriate water gain was defined as a more than 3.6% increase of the mean TBW during normonatraemia in the same patient. Aetiologies of hyponatraemia were divided into two classes according to TBW.
  
  
  RESULTS
  Three hundred and eighty seven patients were enrolled in this study. Ninety nine had normonatraemia and 288 developed hyponatraemia during follow-up. Among 241 episodes with simultaneous bioelectrical impedance analysis measurement, there were 71 cases with appropriate water gain and 170 cases with non-appropriate water gain. Low residual renal function and long duration of PD were associated with development of hyponatraemia by appropriate water gain. On multivariate analysis, old age (≥65-years-of-age), hypoalbuminaemia (<35 g/L), low residual renal function (<2 mL/min per 1.73(2) ) and a high comorbid condition were associated with mortality in the PD patients. The patients with intermediate and high Davies index had an odds ratio of 3.25 for development of hyponatraemia during the follow-up period (95% confidence interval, 2.025-5.215; P < 0.001).
  
  
  CONCLUSIONS
  The prevalence of hyponatraemia increases along with the increased comorbidity status. The comorbidity conditions may be more important than hyponatraemia per se for predicting mortality. Additionally, the preservation of residual renal function may play a role in preventing hyponatraemia.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Yeungnam University Hospital, Daegu, Korea.
authors.forename: Seok Hui
authors.initials: SH
authors.lastname: Kang
authors.forename: Kyu Hyang
authors.initials: KH
authors.lastname: Cho
authors.forename: Jong Won
authors.initials: JW
authors.lastname: Park
authors.forename: Kyung Woo
authors.initials: KW
authors.lastname: Yoon
authors.forename: Jun Young
authors.initials: JY
authors.lastname: Do
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001823:Body Composition; D001834:Body Water / Q000378:metabolism; D016009:Chi-Square Distribution; D015897:Comorbidity; D017097:Electric Impedance; D005260:Female; D006801:Humans; D034141:Hypoalbuminemia / Q000453:epidemiology; D007010:Hyponatremia / Q000175:diagnosis / Q000453:epidemiology* / Q000378:metabolism / Q000401:mortality / Q000628:therapy; D015994:Incidence; D007668:Kidney / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010530:Peritoneal Dialysis / Q000009:adverse effects* / Q000401:mortality; D015995:Prevalence; D011379:Prognosis; D016016:Proportional Hazards Models; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors