Effect of intravenous iron on outcomes of acute kidney injury

Value of serum iron and urine neutrophil gelatinase-associated lipocalin in predicting the mortality of critically ill patients with sepsis

INTRODUCTION

We aimed to investigate the association of iron metabolism-related parameters with 60-day mortality in critically ill patients with sepsis.

METHODS

Serum or urine concentrations of iron metabolism-related parameters on intensive care unit admission were measured in a prospective cohort of 133 eligible patients with sepsis according to the Sepsis-3 criteria, and these values were compared between survivors and nonsurvivors, categorized according to their 60-day survival status. Cox regression analyses were performed to examine the association between iron parameters and 60-day mortality. Kaplan-Meier methods were used to illustrate the differences in survival between different iron parameters.

RESULTS

Of the 133 patients included in the study, 61 (45.8%) had died by day 60. After adjusting for confounding variables, higher concentrations of serum iron (cut-off 9.5 μmol/mL) and higher concentrations of urine neutrophil gelatinase-associated lipocalin (uNGAL; cut-off 169.3 ng/mL) were associated with a significantly greater risk of death in the Cox regression analysis. These two biomarkers combined with Sequential Organ Failure Assessment (SOFA) scores increased the area under the receiver operating characteristic (AUROC) curve to 0.85.

DISCUSSION

These findings suggest that higher concentrations of serum iron and uNGAL are each associated with higher 60-day mortality, and they add significant accuracy to this prediction in combination with SOFA. Abbreviations: uNGAL: urine neutrophil gelatinase-associated lipocalin; ICU: intensive care unit; SOFA: Sequential Organ Failure Assessment; APACHE II: the Acute Physiology and Chronic Health Evaluation II; ELISA: enzyme-linked immunosorbent assay; HR: hazard ratio; CIs: confidence intervals; WBC: white blood cell; TBIL: total bilirubin.

Iron deficiency in sepsis patients managed with divided doses of iron dextran: a prospective cohort study

Iron deficiency (ID) impairs hemoglobin (Hb) synthesis and immune function, both crucial for sepsis patients. We assessed the impact of iron dextran on reticulocyte (Ret) Hb equivalent (Ret-He) and Ret subpopulations in iron-deficient sepsis patients. In this prospective clinical study we enrolled patients with sepsis or septic shock with procalcitonin concentration > 0.5 ng/mL, diagnosed with ID based on Ret-He. Study subjects received divided doses of iron dextran until normalization of Ret-He. The study population included 35 subjects. The median Ret-He increase after 2 doses of iron dextran was 3.0 (IQR 1.9-6.1) pg (p < 0.01) with median time to normalization 4 (IQR 3-5) days. Although no change in Ret percentage [Me 1.5 (IQR 1.1-2.1) vs. Me 1.4 (IQR 1.1-2.4) %, p = 0.39] and number [Me 0.05 (IQR 0.04-0.07) vs. Me 0.05 (IQR 0.03-0.06) 10⁶/µL, p = 0.88] was noted, Ret subpopulations changed significantly (p for all < 0.01). Divided doses of iron dextran relatively quickly normalize Ret-He in iron-deficient sepsis patients. Changes in Ret subpopulations suggest increased erythropoietic activity. Further research is needed to explore the role of intravenous iron in this clinical setting.

Iron Homeostasis and Ferritin in Sepsis-Associated Kidney Injury

Sepsis associated acute kidney injury (SA-AKI) is a common clinical syndrome that occurs among hospitalized patients and significantly impacts mortality. Furthermore, survival after sepsis is intricately dependent on recovery of kidney function. In this review, we discuss the role of iron imbalance in mediating the pathogenic events during sepsis. Intracellular ferritin serves as a repository for iron and prevents iron-mediated injury and may limit the availability of iron to pathogens. Circulating levels of ferritin also increase during sepsis and often correlate with severity of sepsis. Herein, we examine preclinical and clinical data and discuss recent findings that suggest immunomodulatory roles for ferritin. We also discuss the possible mechanistic roles for ferritin in mitigating the pathogenic sequelae of sepsis and highlight current gaps in knowledge.