title: The impact of high serum bicarbonate levels on mortality in hemodialysis patients.
abstract: OBJECTIVE
  The optimal serum bicarbonate level is controversial for patients who are undergoing hemodialysis (HD). In this study, we analyzed the impact of serum bicarbonate levels on mortality among HD patients.
  
  
  METHODS
  Prevalent HD patients were selected from the Clinical Research Center registry for End Stage Renal Disease cohort in Korea. Patients were categorized into quartiles according to their total carbon dioxide (tCO2) levels: quartile 1, a tCO2of < 19.4 mEq/L; quartile 2, a tCO2of 19.4 to 21.5 mEq/L; quartile 3, a tCO2of 21.6 to 23.9 mEq/L; and quartile 4, a tCO2of ≥ 24 mEq/L. Cox regression analysis was used to calculate the adjusted hazard ratio (HR) and confidence interval (CI) for mortality.
  
  
  RESULTS
  We included 1,159 prevalent HD patients, with a median follow-up period of 37 months. Kaplan-Meier analysis revealed that the all-cause mortality was significantly higher in patients from quartile 4, compared to those from the other quartiles (p= 0.009, log-rank test). The multivariate Cox proportional hazard model revealed that patients from quartile 4 had significantly higher risk of mortality than those from quartile 1, 2 and 3, after adjusting for the clinical variables in model 1 (HR, 1.99; 95% CI, 1.15 to 3.45;p= 0.01) and model 2 (HR, 1.82; 95% CI, 1.03 to 3.22;p= 0.04).
  
  
  CONCLUSIONS
  Our data indicate that high serum bicarbonate levels (a tCO2 of ≥ 24 mEq/L) were associated with increased mortality among prevalent HD patients. Further effort might be necessary in finding the cause and correcting metabolic alkalosis in the chronic HD patients with high serum bicarbonate levels.
authors.affiliation: Department of Internal Medicine, College of Medicine, St. Vincent's Hospital, The Catholic University of Korea, Suwon, Korea.
authors.forename: Kyung Yoon
authors.initials: KY
authors.lastname: Chang
authors.affiliation: Department of Internal Medicine, College of Medicine, St. Vincent's Hospital, The Catholic University of Korea, Suwon, Korea.
authors.forename: Hyung Wook
authors.initials: HW
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, College of Medicine, St. Vincent's Hospital, The Catholic University of Korea, Suwon, Korea.
authors.forename: Woo Jeong
authors.initials: WJ
authors.lastname: Kim
authors.affiliation: College of Medicine, Bucheon St. Mary's Hospital, The Catholic University of Korea, Bucheon, Korea.
authors.forename: Yong Kyun
authors.initials: YK
authors.lastname: Kim
authors.affiliation: Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Su-Hyun
authors.initials: SH
authors.lastname: Kim
authors.affiliation: College of Medicine, Bucheon St. Mary's Hospital, The Catholic University of Korea, Bucheon, Korea.
authors.forename: Ho Chul
authors.initials: HC
authors.lastname: Song
authors.affiliation: College of Medicine, Uijeongbu St. Mary's Hospital, The Catholic University of Korea, Uijeongbu, Korea.
authors.forename: Young Ok
authors.initials: YO
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, College of Medicine, St. Vincent's Hospital, The Catholic University of Korea, Suwon, Korea.
authors.forename: Dong Chan
authors.initials: DC
authors.lastname: Jin
authors.affiliation: College of Medicine, Bucheon St. Mary's Hospital, The Catholic University of Korea, Bucheon, Korea.
authors.forename: Euy Jin
authors.initials: EJ
authors.lastname: Choi
authors.affiliation: College of Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea.
authors.forename: Chul Woo
authors.initials: CW
authors.lastname: Yang
authors.affiliation: Kyungpook National University School of Medicine, Daegu, Korea.
authors.forename: Yong-Lim
authors.initials: YL
authors.lastname: Kim
authors.affiliation: Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Nam-Ho
authors.initials: NH
authors.lastname: Kim
authors.affiliation: Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Shin-Wook
authors.initials: SW
authors.lastname: Kang
authors.affiliation: Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Yon-Su
authors.initials: YS
authors.lastname: Kim
authors.affiliation: College of Medicine, Uijeongbu St. Mary's Hospital, The Catholic University of Korea, Uijeongbu, Korea.
authors.forename: Young Soo
authors.initials: YS
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D001639:Bicarbonates / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D007676:Kidney Failure, Chronic / Q000097:blood / Q000175:diagnosis / Q000401:mortality / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D015995:Prevalence; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012042:Registries; D006435:Renal Dialysis / Q000009:adverse effects / Q000401:mortality*; D056910:Republic of Korea / Q000453:epidemiology; D012307:Risk Factors; D016896:Treatment Outcome; D015854:Up-Regulation
chemical_list: D001639:Bicarbonates; D015415:Biomarkers
keywords: Alkalosis; Bicarbonates; Mortality; Renal dialysis