The associations among iron metabolism markers, iron supplementation regimen, and sepsis-induced myocardial injury: a retrospective study

Background Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response, among which sepsis-induced myocardial injury (SIMI) is a common and severe complication. Iron metabolic disorders are closely associated with infection, inflammation, oxidative stress, and organ damage. However, their relationship with the prognosis of sepsis and SIMI, as well as the safety and benefits of iron supplementation therapy, remain unclear. This study aimed to investigate these associations. Methods Based on the MIMIC-IV database, a retrospective cohort analysis was conducted in adult patients with sepsis admitted to the intensive care unit (ICU). Iron metabolism biomarkers and clinical data were extracted. Analytical methods included Cox regression, restricted cubic splines (RCS), and propensity score matching (PSM). Results A total of 3,360 patients were enrolled. Hyperferritinemia was associated with an increased 30-day mortality (hazard ratio (HR) = 1.56, 95% confidence interval (CI): 1.195–2.038, p < 0.001). In contrast, higher transferrin levels (HR = 0.552, p < 0.001) and higher total iron-binding capacity (TIBC) (HR = 0.559, p < 0.001) exhibited protective effects. Serum iron levels did not correlate well with mortality. RCS analysis untangled a nonlinear relationship between iron metabolism markers and sepsis, whereas a linear association was observed between ferritin and SIMI. After propensity score matching (PSM), intravenous iron supplementation was associated with a lower 30-day mortality rate (10.16% vs. 27.81%, HR = 0.251, p < 0.001). Conclusion Ferritin, transferrin, and total iron-binding capacity (TIBC) are of significant value for risk stratification in sepsis. Intravenous iron supplementation may improve short-term prognosis without increasing the risk of subsequent SIMI; however, this conclusion requires validation through prospective studies.