ferritin

Overview

Ferritin is a ubiquitous intracellular iron-storage protein found across virtually all living organisms, serving as the primary depot for bioavailable iron in mammals. It is a hollow, spherical nanocage composed of 24 protein subunits—heavy (FTH1) and light (FTL) chains—that can sequester up to approximately 4,500 iron atoms in a mineralized ferrihydrite core. By buffering free iron within cells and tissues, ferritin prevents iron-catalyzed oxidative damage while simultaneously maintaining a reservoir that can be mobilized in response to physiological demand. Serum ferritin, the fraction secreted into the bloodstream, circulates at concentrations that closely reflect total body iron stores under homeostatic conditions, making it one of the most widely used clinical biomarkers in laboratory medicine. Normal reference ranges vary by age, sex, and physiological state, and deviations in either direction—hypoferritinemia signaling iron-deficiency states or hyperferritinemia indicating iron overload, inflammation, or tissue damage—carry distinct diagnostic implications.

Beyond its canonical role in iron metabolism, ferritin has attracted growing attention in immunology, vaccine engineering, and oncology. Its naturally self-assembling, symmetric architecture makes it an attractive scaffold for multivalent antigen display, and its interaction with acute-phase inflammatory mediators such as interleukin-6 and C-reactive protein positions it as an integrated sensor of systemic inflammation. In pathological states ranging from hematologic malignancies and post-transplant iron overload to metabolic disorders and severe infectious disease, ferritin levels reflect the convergence of iron dysregulation and immune activation, underscoring its dual identity as both a structural protein and a functional biomarker.

Focus of Latest Publications

Iron Status and Clinical Biomarker Applications

A significant cluster of recent publications has reinforced ferritin's central role as a quantitative marker of iron reserves in diverse clinical populations. In studies of iron-deficiency anemia, hemoglobin and ferritin levels were co-measured as paired markers of iron status—hemoglobin reflecting functional iron utilization and ferritin capturing stored reserves—demonstrating the complementary diagnostic value of these two indices in early childhood populations (PMID 42118173). In athletes, urinary hepcidin-to-creatinine ratios were found to correlate strongly with serum hepcidin and to be positively associated with ferritin, suggesting that urinary hepcidin measurement can serve as a non-invasive proxy for underlying iron dynamics in female athletes prone to iron-deficiency anemia (PMID 42173680). This association situates ferritin within the hepcidin-iron regulatory axis, where hepcidin-mediated internalization of ferroportin controls iron egress from storage compartments monitored by ferritin.

In hemodialysis patients, ferritin was measured alongside serum iron, transferrin saturation, and total iron binding capacity to characterize iron metabolism in the context of anemia of inflammation (PMID 42151276). This study examined cross-talk between cytokine genes and microRNAs, with proinflammatory cytokines—notably interleukin-6—known to upregulate ferritin synthesis as part of the acute-phase response, thereby decoupling serum ferritin from true iron stores and complicating its interpretation in inflammatory states. In a serum metabolomic investigation of early childhood iron-deficiency anemia, gas chromatography-mass spectrometry–based metabolic profiling was paired with ferritin and hepcidin measurements, allowing investigators to identify metabolomic signatures that parallel iron status indicators (PMID 42118173).

Ferritin in Bariatric Surgery and Metabolic Research

Two prospective studies examined ferritin as a predictive biomarker in the bariatric surgery context. The first assessed serum ferritin alongside Folate and vitamin B12 levels to examine their roles in weight loss after bariatric surgery, recognizing that restrictive and malabsorptive procedures alter micronutrient absorption profiles in ways that directly affect iron stores (PMID 42179354). The second study developed and validated a clinical prediction model for postoperative weight regain using preoperative inflammatory, metabolic, and ferritin biomarkers, positioning ferritin within a multivariate panel of metabolic biomarkers that collectively predict long-term surgical outcomes (PMID 41979200). These findings suggest that ferritin's pre-surgical value may encode information about inflammatory tone and metabolic reserve that is not captured by weight-based metrics alone.

Ferritin in Hematologic Malignancies and Transplant Medicine

In myeloproliferative neoplasms (MPNs)—including polycythemia vera, essential thrombocytosis, myelofibrosis, MPN-unclassifiable, and overt myelofibrosis—a study examining functional iron parameters revealed that MPN patients exhibited lower hemoglobin and paradoxically higher ferritin compared to a reference population (SHIP cohort), with the physiological positive correlation between ferritin and hemoglobin observed in healthy individuals being inverted in MPN patients (PMID 42176009). zinc protoporphyrin (ZPP) was used to refine iron-deficiency markers in this setting, highlighting the complexity of interpreting ferritin in the context of clonal hematopoiesis and inflammatory signaling intrinsic to MPNs.

In pediatric hematopoietic stem cell transplantation (HSCT) for nonmalignant hematological disorders, ferritin and liver iron concentration were evaluated as estimators of iron overload to determine HSCT eligibility. A key finding was that neither ferritin nor liver iron concentration was definitively associated with poorer HSCT outcomes in pediatric cohorts, cautioning against over-reliance on ferritin thresholds alone for pre-transplant risk stratification (PMID 41637630). In adult allogeneic HSCT recipients with AML/MDS, a propensity score-matched study of deferasirox chelation therapy initiated six months post-transplant demonstrated that ferritin levels declined from approximately 1,700 µg/L to below 1,000 µg/L by 18 months, corroborating the efficacy of post-transplant chelation strategies in reducing iron burden (PMID 41811968).

Ferritin as an Inflammation Biomarker in Severe COVID-19

A single-center observational cohort study of severe COVID-19 identified statistically significant associations between elevated ferritin and coagulopathy, alongside other inflammatory and coagulation mediators including leptin, interleukin-6, C-reactive protein, neutrophil-lymphocyte ratio, fibrinogen, erythrocyte sedimentation rate, and L-lactate dehydrogenase (PMID 42065184). This cross-talk between inflammation and coagulation, with ferritin functioning as an acute-phase reactant, reinforces the concept that hyperferritinemia in severe COVID-19 reflects a cytokine-driven inflammatory state rather than true iron excess.

Ferritin as a Nanoparticle Platform for Vaccine Engineering

A distinct and rapidly expanding line of research exploits ferritin's self-assembling properties to engineer multivalent nanoparticle vaccines. One study demonstrated that epitopes from feline herpesvirus 1 (FHV-1) glycoprotein B (FHB1 and FHB2) fused to ferritin produced FHB1F and FHB2F nanoparticles that induced robust humoral and mucosal immunity in preclinical models (PMID 42106031). The ferritin nanocage scaffold presents antigens in a repetitive, multivalent geometry that efficiently engages B-cell receptors and promotes germinal center responses. A complementary study showed that antigen-specific B cells function as antigen-presenting cells for CD4+ T cell priming across distinct nanoparticle platforms including both AP205 and ferritin, with MHC class II-mediated antigen presentation by B cells playing a previously underappreciated role in T-dependent antibody responses (PMID 42085184). These findings illuminate the immunological mechanism by which ferritin nanoparticles activate adaptive immunity beyond simple antigen delivery.

Key Publications

• Jun Labile iron starvation in embryonic Kupffer cells aggravates MASH via mitochondrial failure and macrophage dysfunction. (Cell death & disease, 2026, PMID 42310295): "Conversely, ferritin depletion restores emKC labile iron levels, mitigates mitochondrial damage, and attenuates disease severity."
• Jun Association of Serum Angiopoietin-Like Protein 7 With Ferroptosis-Related Proteins in Patients With Metabolic Dysfunction-Associated Fatty Liver Disease. (FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 2026, PMID 42247282): "Serum levels of ANGPTL7, TNF-α, IL-6, ACSL4, Keap-1, HO-1, and ferritin were significantly increased, while IL-10, GPX4, and Nrf2 levels were decreased in MAFLD patients when compared with the Con group (MAFLD vs. Con, all p < 0.001)."
• Jun Development and validation of a clinical prediction model for postoperative weight regain after bariatric surgery using inflammatory, metabolic, and ferritin biomarkers. (Archives of endocrinology and metabolism, 2026, PMID 41979200): "by using preoperative inflammatory, metabolic, and ferritin as biomarkers."
• Jun Potential Usefulness of Urinary Hepcidin Measurement for Iron Deficiency Anemia in Female Athletes. (European journal of sport science, 2026, PMID 42173680): "Urinary hepcidin/creatinine showed a strong correlation with serum hepcidin and was positively associated with ferritin, suggesting that it reflects underlying iron dynamics."
• Jun Self-assembling ferritin nanoparticles displaying glycoprotein B epitopes induce robust humoral and mucosal immunity against feline herpesvirus 1. (International journal of biological macromolecules, 2026, PMID 42106031): "In this study, epitopes from FHV-1 glycoprotein B (FHB1 and FHB2) were fused to ferritin to create FHB1F and FHB2F nanoparticles."
• May Multivalent nanoparticles activate T-dependent antibody response via antigen presentation by both B cells and dendritic cells. (Cell reports, 2026, PMID 42085184): "Here, we show that antigen-specific B cells function as antigen-presenting cells (APCs) for CD4+ T cell priming across distinct nanoparticle platforms, including AP205 and ferritin."
• May Impact of iron overload on hematopoietic stem cell transplantation in pediatric patients with nonmalignant hematological disorders. (Blood advances, 2026, PMID 41637630): "Ferritin and liver iron concentration (LIC) are used to estimate the degree of iron overload to determine eligibility for HSCT, but neither marker has been definitively associated with poorer HSCT outcomes in pediatric cohorts."
• May Deferasirox 6 months after allo-HSCT in AML/MDS: a prospective propensity-matched study. (Blood advances, 2026, PMID 41811968): "Ferritin level decreased from 1700 μg/L to <1000 μg/L by 18 months."
• May The Effect of Ferritin on Weight Loss in Patients Undergoing Bariatric Surgery: A Prospective Cohort Study. (Journal of investigative surgery : the official journal of the Academy of Surgical Research, 2026, PMID 42179354): "This study aimed to assess serum ferritin, folate, and vitamin B12 levels and examine their roles in weight loss after bariatric surgery (BS)."
• May Value of functional iron parameters in diagnostic re-assessment of MPN: refinement of iron-deficiency markers by zinc protoporphyrin (ZPP). (Annals of hematology, 2026, PMID 42176009): "Compared with SHIP, MPN patients had lower hemoglobin and higher ferritin, and the physiological positive correlation between ferritin and hemoglobin observed in SHIP was reversed in MPN patients."