Approximation of bicarbonate concentration using serum total carbon dioxide concentration in patients with non-dialysis chronic kidney disease
Keiji Hirai1 , Saori Minato1 , Shohei Kaneko1 , Katsunori Yanai1 , Hiroki Ishii1 , Taisuke Kitano1 , Mitsutoshi Shindo1 , Haruhisa Miyazawa1 , Kiyonori Ito1 , Yuichirou Ueda1 , Yoshio Kaku1 , Taro Hoshino1 , Tatsuro Watano2 , Shinji Fujino2 , Susumu Ookawara1 , Kiyoka Omoto2 , Yoshiyuki Morishita1
1Division of Nephrology, First Department of Integrated Medicine, and 2Department of Laboratory Medicine, Saitama Medical Center, Jichi Medical University, Saitama, Japan
Correspondence to: Keiji Hirai
Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, 1-847 Amanuma-cho, Omiya-ku, Saitama, Saitama 330-8503, Japan. E-mail: keijihirai@kfy.biglobe.ne.jp

Edited by Sejoong Kim, Seoul National University, Seoul, Korea
Received: March 6, 2019; Revised: May 21, 2019; Accepted: May 24, 2019; Published online: August 5, 2019.
© The Korean Society of Nephrology. All rights reserved.

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Background: We investigated the relationship between serum total carbon dioxide (CO2) and bicarbonate ion (HCO3-) concentrations in pre-dialysis chronic kidney disease (CKD) patients and devised a formula for predicting low bicarbonate (HCO3- < 24 mmol/L) and high bicarbonate (HCO3- ≥ 24 mmol/L) using clinical parameters.
Methods: In total, 305 samples of venous blood collected from 207 pre-dialysis patients assessed by CKD stage (G1 + G2, 46; G3, 50; G4, 51; G5, 60) were investigated. The relationship between serum total CO2 and HCO3- concentrations was analyzed using Pearson’s correlation coefficient. An approximation formula was developed using clinical parameters correlated independently with HCO3- concentration. Diagnostic accuracy of serum total CO2 and the approximation formula was evaluated by receiver operating characteristic curve analysis and a 2 × 2 table.
Results: Serum total CO2 correlated strongly with HCO3- concentration (r = 0.91; P < 0.001). The following approximation formula was obtained by a multiple linear regression analysis: HCO3- (mmol/L) = total CO2 - 0.5 × albumin - 0.1 × chloride - 0.01 × (estimated glomerular filtration rate + blood glucose) + 15. The areas under the curves of serum total CO2 and the approximation formula for detection of low bicarbonate and high bicarbonate were 0.981, 0.996, 0.993, and 1.000, respectively. This formula had superior diagnostic accuracy compared with that of serum total CO2 (86.6% vs. 81.3%).
Conclusion: Serum total CO2 correlated strongly with HCO3- concentration in pre-dialysis CKD patients. An approximation formula including serum total CO2 showed superior diagnostic accuracy for low and high bicarbonate compared with serum total CO2.
Keywords: Acid base balance, Bicarbonates, Carbon dioxide, Chronic kidney disease


e-submission

This Article


Cited By Articles
  • CrossRef (0)
  • PMC (0)
  • SCOPUS (0)

Services
Social Network Service

Archives

Indexed/Covered by