{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,12]],"date-time":"2026-01-12T11:49:28Z","timestamp":1768218568501,"version":"3.49.0"},"reference-count":14,"publisher":"PeerJ","license":[{"start":{"date-parts":[[2026,1,12]],"date-time":"2026-01-12T00:00:00Z","timestamp":1768176000000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Serum osmolarity, reflecting fluid and electrolyte balance, may serve as a prognostic marker in critically ill patients, but its role in COVID-19 is not well established. This study evaluated the association between admission serum osmolarity and in-hospital mortality in critically ill COVID-19 patients.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We conducted a retrospective study including 267 critically ill COVID-19 patients admitted from the ED to the ICU of a tertiary-care hospital between March 2020 and April 2022. Data on demographics, thoracic computed tomography (CT) findings, vasopressor use, ventilation support, laboratory values, and in-hospital mortality were obtained. Serum osmolarity was calculated using the formula. The primary outcome was in-hospital mortality; secondary outcomes included vasopressor use, endotracheal intubation (ETI), and laboratory parameters. Statistical analyses included Mann\u2013Whitney U and chi-square tests, logistic regression, and receiver operating characteristic (ROC) curve analysis.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Of 267 patients, 203 were non-survivors and 64 survivors (mortality 76%); mean age was 53.8\u00a0\u00b1\u00a012.3 years, 59.6% male. Survivors had higher median serum osmolarity (288.37\n                      <jats:italic>vs.<\/jats:italic>\n                      285.75 mOsm\/L,\n                      <jats:italic>p<\/jats:italic>\n                      \u00a0=\u00a00.034) and sodium (Na) (135\n                      <jats:italic>vs.<\/jats:italic>\n                      133 mEq\/L,\n                      <jats:italic>p<\/jats:italic>\n                      \u00a0=\u00a00.004). Sodium demonstrated slightly superior discrimination (AUC = 0.620) compared to osmolarity (area under the curve (AUC) = 0.588). In multivariate logistic regression, serum sodium (OR = 0.89, 95% CI 0.82\u20130.97), inotropic agent use (OR = 3.73, 95% CI [1.65\u20138.42]), and endotracheal intubation (OR = 5.20, 95% CI [2.11\u201312.84]) were independent predictors of mortality. The model\u2019s c-statistic was 0.713 (95% CI [0.654\u20130.771]) with 70.4% sensitivity and 65.8% specificity.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Lower admission serum osmolarity and hyponatremia were independently associated with increased in-hospital mortality in critically ill COVID-19 patients. Although Na slightly outperformed calculated osmolarity, the latter remains a practical, integrative prognostic tool for early risk stratification. Prospective studies should evaluate whether timely correction of hypo-osmolar or hyponatremic states improves outcomes.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.7717\/peerj.20590","type":"journal-article","created":{"date-parts":[[2026,1,12]],"date-time":"2026-01-12T08:46:27Z","timestamp":1768207587000},"page":"e20590","source":"Crossref","is-referenced-by-count":0,"title":["Serum osmolarity as a predictor of mortality in ICU COVID-19 patients: a retrospective analysis"],"prefix":"10.7717","volume":"14","author":[{"given":"Mehmet","family":"Toptas","sequence":"first","affiliation":[{"name":"Department of Anesthesiology and Reanimation, \u0130stanbul Training and Research Hospital, \u0130stanbul, Fatih, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"\u00d6zlem","family":"Dikme","sequence":"additional","affiliation":[{"name":"Department of Emergency Medicine, \u0130stanbul Training and Research Hospital, \u0130stanbul, Fatih, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ozgur","family":"Dikme","sequence":"additional","affiliation":[{"name":"Department of Emergency Medicine, \u0130stanbul Training and Research Hospital, \u0130stanbul, Fatih, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Abdurrahman","family":"T\u00fcnay","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology and Reanimation, \u0130stanbul Training and Research Hospital, \u0130stanbul, Fatih, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mensure","family":"Yilmaz Cakirgoz","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology and Reanimation, \u0130zmir City University, \u0130zmir, Bayrakli, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"\u0130brahim","family":"Akko\u00e7","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology and Reanimation, Basaksehir Cam and sakura City Hospital, \u0130stanbul,  Basaksehir, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"4443","published-online":{"date-parts":[[2026,1,12]]},"reference":[{"issue":"2","key":"10.7717\/peerj.20590\/ref-1","doi-asserted-by":"publisher","first-page":"e072784","DOI":"10.1136\/bmjopen-2023-072784","article-title":"Predictors of mortality in hospitalized patients with COVID-19: a 1-year case-control study","volume":"14","author":"Camacho-Dom\u00ednguez","year":"2024","journal-title":"BMJ Open"},{"issue":"1","key":"10.7717\/peerj.20590\/ref-2","doi-asserted-by":"publisher","first-page":"4","DOI":"10.13188\/2469-4045.1000007","article-title":"Ramadan fasting and its influence on serum osmolality in emergency patients","volume":"2","author":"Dikme","year":"2016","journal-title":"The Journal of Emergency and Critical Care Medicine"},{"issue":"3","key":"10.7717\/peerj.20590\/ref-3","first-page":"185","article-title":"Measurement of serum osmolality and its application in 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