Association of iron-related parameters with the development of sepsis-associated acute kidney injury.

OBJECTIVE: To investigate the associations of iron-related parameters, including serum ferritin (SF), serum iron (SI), and transferrin saturation (TSAT), with the development of sepsis-associated acute kidney injury (SA-AKI). METHODS: This retrospective study included 808 patients with sepsis admitted to the Second Affiliated Hospital of Dalian Medical University between January 1, 2015 and September 30, 2024. Data were obtained from the Yidu Cloud database and the hospital electronic medical record system. Patients were classified according to whether acute kidney injury (AKI) was clinically diagnosed within 48 hours of admission. Group differences were assessed using appropriate parametric or nonparametric tests, and correlations using Spearman analysis. SF, SI, and TSAT were categorized into quartiles to examine trends in AKI incidence. Two multivariable logistic regression models-a clinical model and the clinical model plus SF-were constructed to evaluate factors associated with SA-AKI. Receiver operating characteristic (ROC) curves were used to assess discriminatory ability, and the areas under the curves (AUCs) were compared using the DeLong test. Model calibration was assessed using the Hosmer-Lemeshow test and calibration plots, and internal validation was performed using 1,000 bootstrap resamples. RESULTS: Among the 808 patients, 310 (38.4%) had SA-AKI. In Model 2, higher SF remained associated with SA-AKI (OR 2.479 per 100-ng/mL increase, 95% CI 2.123,2.894, P < 0.001). Adding SF to the clinical model increased the AUC from 0.730 to 0.846 (95% CI 0.085,0.147, P < 0.001). Both models showed acceptable calibration, and bootstrap estimates were generally consistent with the original results. For SF alone, the AUC was 0.793 (95% CI 0.761, 0.826), and the optimal cutoff was 525.56 ng/mL, with a sensitivity of 0.710 and a specificity of 0.765. CONCLUSIONS: Higher SF was associated with SA-AKI and improved the discriminatory ability of the clinical model. SF may provide additional information for the clinical assessment and identification of SA-AKI in patients with sepsis.