{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T18:10:21Z","timestamp":1789755021612,"version":"4.0.1"},"reference-count":23,"publisher":"Public Library of Science (PLoS)","issue":"9","license":[{"start":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T00:00:00Z","timestamp":1789689600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100011326","name":"Shiga University of Medical Science","doi-asserted-by":"publisher","award":["Intramural Research Grant"],"award-info":[{"award-number":["Intramural Research Grant"]}],"id":[{"id":"10.13039\/501100011326","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:sec id=\"sec001\">\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>\n                      Respiratory failure is the leading cause of death in amyotrophic lateral sclerosis (ALS). Early detection of CO\n                      <jats:sub>2<\/jats:sub>\n                      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.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec002\">\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>\n                      We investigated whether the serum sodium-chloride difference (Na-Cl value), calculated from routine blood tests, could serve as a screening marker for CO\n                      <jats:sub>2<\/jats:sub>\n                      retention in ALS patients.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec003\">\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      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 (HCO\n                      <jats:sub>3<\/jats:sub>\n                      <jats:sup>\u2212<\/jats:sup>\n                      , PCO\n                      <jats:sub>2<\/jats:sub>\n                      ), performed receiver operating characteristic (ROC) analysis for detecting CO\n                      <jats:sub>2<\/jats:sub>\n                      retention (PCO\n                      <jats:sub>2<\/jats:sub>\n                      \u2009\u2265\u200945 mmHg), and examined relationships with respiratory function (%FVC).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec004\">\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Na-Cl value showed strong correlation with HCO\n                      <jats:sub>3<\/jats:sub>\n                      <jats:sup>\u2212<\/jats:sup>\n                      (r\u2009=\u20090.78, p\u2009&lt;\u20090.001) and PCO\n                      <jats:sub>2<\/jats:sub>\n                      (r\u2009=\u20090.71, p\u2009&lt;\u20090.001). Na-Cl\u2009\u2265\u200937 mEq\/L demonstrated sensitivity of 85.11% and specificity of 69.57% for detecting PCO\n                      <jats:sub>2<\/jats:sub>\n                      \u2009\u2265\u200945 mmHg, with negative predictive value of 87.27% (AUC\u2009=\u20090.842). Na-Cl\u2009\u2265\u200939 mEq\/L achieved specificity of 92.75%. Patients with %FVC\u2009&lt;\u200950% had significantly higher Na-Cl, PCO\n                      <jats:sub>2<\/jats:sub>\n                      , and HCO\n                      <jats:sub>3<\/jats:sub>\n                      <jats:sup>\u2212<\/jats:sup>\n                      \u2009values.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec005\">\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>\n                      Serum Na-Cl value serves as a simple, noninvasive screening marker for CO\n                      <jats:sub>2<\/jats:sub>\n                      retention in ALS. Na-Cl\u2009\u2265\u200937 mEq\/L warrants blood gas analysis, while Na-Cl\u2009\u2265\u200939 mEq\/L provides specificity &gt;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.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1371\/journal.pone.0358772","type":"journal-article","created":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T17:37:11Z","timestamp":1789753031000},"page":"e0358772","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["Serum Na-Cl value from routine blood tests reflects CO2 retention in amyotrophic lateral sclerosis"],"prefix":"10.1371","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-0968-5880","authenticated-orcid":true,"given":"Isamu","family":"Yamakawa","sequence":"first","affiliation":[{"name":"Shiga University of Medical Science","place":["Otsu, Shiga, Japan"],"department":["Department of 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