Serum iron profile dynamics and short-term mortality in critically ill patients: A retrospective cohort study
Keywords:
Iron, Ferritin, Intensive Care Units, Mortality, Prognosis, SOFA, Critical IllnessAbstract
Iron metabolism dysregulation is a common feature of critical illness and may affect outcomes through its roles in oxygen transport, immune regulation, and oxidative stress. Although serum iron and ferritin have been proposed as prognostic biomarkers in intensive care unit (ICU) patients, their temporal changes and associations with short-term mortality remain unclear. This study evaluated the relationship between serial measurements of serum iron and ferritin and in-hospital mortality. To evaluate the association between serial (day-1 and day-7) serum iron and ferritin measurements and 7-day in-hospital mortality in a cohort of critically ill patients, and to assess the discriminative performance of a multivariable model including these biomarkers. This retrospective cohort study included 413 consecutive adult patients admitted to the intensive care unit (ICU) of a tertiary referral teaching hospital between January and December 2025. Clinical and laboratory data were retrospectively extracted from electronic medical records. Serum iron and ferritin concentrations measured on ICU admission (day 1) and on day 7, or at the last available assessment for patients discharged or deceased before day 7, were evaluated for their association with 7-day in-hospital mortality using multivariable logistic regression analysis. The overall 7-day mortality rate was 23.0% (95/413). After adjustment for age, sex, body mass index, and ICU length of stay, higher day 1 iron (OR: 0.517; 95% CI: 0.390–0.686; P<0.001) and ferritin levels (OR: 0.896; 95% CI: 0.857–0.937; P<0.001) were independently associated with lower mortality. In contrast, elevated day 7 iron (OR: 1.858; 95% CI: 1.426–2.421; P<0.001) and ferritin levels (OR: 1.115; 95% CI: 1.066–1.166; P<0.001) were associated with increased mortality. The model demonstrated high discrimination (AUROC 0.996; 95% CI 0.988–1.000). Serum iron and ferritin demonstrate a time-dependent biphasic association with short-term mortality. Serial monitoring may improve risk stratification in critically ill patients.
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