Serum Na-Cl value from routine blood tests reflects CO₂ retention in amyotrophic lateral sclerosis
- 1Department of Neurology, Shiga University of Medical Science, Otsu, Shiga, Japan
Abstract
Background: Respiratory failure is the leading cause of death in amyotrophic lateral sclerosis (ALS). Early detection of CO2 retention is crucial for assessing respiratory failure severity and guiding noninvasive positive pressure ventilation (NPPV) management. However, arterial blood gas analysis is invasive and uncomfortable for routine monitoring. Objective: We investigated whether the serum sodium-chloride difference (Na-Cl value), calculated from routine blood tests, could serve as a screening marker for CO2 retention in ALS patients. Methods: This retrospective study included 88 ALS patients with 116 paired samples of arterial blood gas and serum electrolyte data. We analyzed correlations between Na-Cl value and blood gas parameters (HCO3−, PCO2), performed receiver operating characteristic (ROC) analysis for detecting CO2 retention (PCO2 ≥ 45 mmHg), and examined relationships with respiratory function (%FVC). Results: Na-Cl value showed strong correlation with HCO3− (r = 0.78, p < 0.001) and PCO2 (r = 0.71, p < 0.001). Na-Cl ≥ 37 mEq/L demonstrated sensitivity of 85.11% and specificity of 69.57% for detecting PCO2 ≥ 45 mmHg, with negative predictive value of 87.27% (AUC = 0.842). Na-Cl ≥ 39 mEq/L achieved specificity of 92.75%. Patients with %FVC < 50% had significantly higher Na-Cl, PCO2, and HCO3− values. Conclusions: Serum Na-Cl value serves as a simple, noninvasive screening marker for CO2 retention in ALS. Na-Cl ≥ 37 mEq/L warrants blood gas analysis, while Na-Cl ≥ 39 mEq/L provides specificity >90%. This marker can be calculated from routine blood tests without additional cost, making it suitable for frequent monitoring and reducing the risk of missing intervention timing.
Related
- Transcutaneous Carbon Dioxide Monitoring in Amyotrophic Lateral Sclerosis: A Scoping Review
- The value of a family history to distinguish monogenic from polygenic amyotrophic lateral sclerosis
- Amyotrophic Lateral Sclerosis in a Patient Treated for Neurosyphilis: A Case Report
- The prevalence of type 2 diabetes mellitus among people with amyotrophic lateral sclerosis is increasing in the United States
- Advancing the Translational Pipeline: From In Vivo and In Vitro 2D Models to Next-Generation Cell Culture Models for Amyotrophic Lateral Sclerosis Modelling and Drug Discovery
BibTeX
@article{yamakawa2026serum,
title = {{Serum Na-Cl value from routine blood tests reflects CO₂ retention in amyotrophic lateral sclerosis}},
author = {Isamu Yamakawa and Ryota Tamura and Hiroyuki Yabata and Takahito Tsukamoto and Shuhei Kobashi and Yoshitaka Tamaki and Nobuhiro Ogawa and Akihiro Kitamura and Makoto Urushitani},
journal = {PLOS One},
year = {2026},
month = sep,
doi = {10.1371/journal.pone.0358772},
url = {https://doi.org/10.1371/journal.pone.0358772},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Serum Na-Cl value from routine blood tests reflects CO₂ retention in amyotrophic lateral sclerosis
AU - Isamu Yamakawa
AU - Ryota Tamura
AU - Hiroyuki Yabata
AU - Takahito Tsukamoto
AU - Shuhei Kobashi
AU - Yoshitaka Tamaki
AU - Nobuhiro Ogawa
AU - Akihiro Kitamura
AU - Makoto Urushitani
PY - 2026
DA - 2026/09/18
JO - PLOS One
DO - 10.1371/journal.pone.0358772
UR - https://doi.org/10.1371/journal.pone.0358772
AB - Background: Respiratory failure is the leading cause of death in amyotrophic lateral sclerosis (ALS). Early detection of CO2 retention is crucial for assessing respiratory failure severity and guiding noninvasive positive pressure ventilation (NPPV) management. However, arterial blood gas analysis is invasive and uncomfortable for routine monitoring. Objective: We investigated whether the serum sodium-chloride difference (Na-Cl value), calculated from routine blood tests, could serve as a screening marker for CO2 retention in ALS patients. Methods: This retrospective study included 88 ALS patients with 116 paired samples of arterial blood gas and serum electrolyte data. We analyzed correlations between Na-Cl value and blood gas parameters (HCO3−, PCO2), performed receiver operating characteristic (ROC) analysis for detecting CO2 retention (PCO2 ≥ 45 mmHg), and examined relationships with respiratory function (%FVC). Results: Na-Cl value showed strong correlation with HCO3− (r = 0.78, p < 0.001) and PCO2 (r = 0.71, p < 0.001). Na-Cl ≥ 37 mEq/L demonstrated sensitivity of 85.11% and specificity of 69.57% for detecting PCO2 ≥ 45 mmHg, with negative predictive value of 87.27% (AUC = 0.842). Na-Cl ≥ 39 mEq/L achieved specificity of 92.75%. Patients with %FVC < 50% had significantly higher Na-Cl, PCO2, and HCO3− values. Conclusions: Serum Na-Cl value serves as a simple, noninvasive screening marker for CO2 retention in ALS. Na-Cl ≥ 37 mEq/L warrants blood gas analysis, while Na-Cl ≥ 39 mEq/L provides specificity >90%. This marker can be calculated from routine blood tests without additional cost, making it suitable for frequent monitoring and reducing the risk of missing intervention timing.
SN - 1932-6203
ER -