Metabolic hyperferritinaemia (MHF) in Bariatric Surgery Candidates: Prevalence and Cross-Sectional Associations with Liver Function and Metabolic Markers

Technical Summary: Metabolic Hyperferritinaemia in Bariatric Surgery Candidates

Problem Statement
Metabolic hyperferritinaemia (MHF), characterized by elevated serum ferritin levels in the context of metabolic dysfunction (e.g., obesity, insulin resistance), is linked to liver damage, type 2 diabetes, and cardiovascular disease. While previous research has established associations between iron metabolism and metabolic disorders, there is a lack of large-sample, quantitative evidence regarding the clinical characteristics and multisystem metabolic correlations of MHF specifically within morbidly obese populations. Furthermore, the precise mechanisms linking iron overload to specific metabolic disorders in this high-risk group remain insufficiently elucidated, and targeted interventions are limited due to a lack of unified diagnostic standards and comprehensive data.

Methodology
This study employed a cross-sectional case-control design utilizing preoperative baseline data from 695 patients scheduled for primary bariatric surgery at a single center between 2019 and 2020. All participants met the 2022 IFSO Surgical Guidelines (BMI > 32.5, or BMI > 25 with metabolic syndrome components).

• Group Stratification: Patients were divided into an MHF group and a normal iron group based on gender-specific serum ferritin cut-offs: >300 ng/mL for males and >200 ng/mL for females (MHF group) versus ≤300 ng/mL (males) and ≤200 ng/mL (females) (Control group).
• Statistical Analysis: The study compared 14 core metabolic and clinical indicators between the two groups using independent-samples t-tests for normally distributed data and Wilcoxon rank-sum tests for non-normally distributed data. Correlation analyses were performed to assess the relationship between serum ferritin levels and key parameters.
• Ethical Compliance: The study was approved by the Scientific Research Ethics Committee of the First Affiliated Hospital of Jinan University and adhered to the 1964 Helsinki Declaration.

Key Results

• Prevalence: The overall prevalence of MHF in the cohort was 18.51% (129/695). There was a significant gender disparity, with males exhibiting a much higher prevalence (32.67%) compared to females (10.54%).
• BMI Correlation: A clear upward trend in MHF prevalence was observed with increasing BMI. The prevalence rose from 11.11% in the overweight group (BMI 24–27.9) to 22.73% in the Obesity III group (BMI ≥ 40).
• Metabolic and Clinical Associations: The MHF group demonstrated significantly abnormal profiles across multiple systems compared to the control group:
  • Liver Function: Significant elevations were found in ALT, AST, and notably γ-GT (gamma-glutamyl transferase).
  • Glycolipid Metabolism: The MHF group showed worse profiles in total cholesterol, triglycerides, HDL-C, LDL-C, fasting glucose, insulin, C-peptide, and HbA1c.
  • Hematology: Significant differences were noted in hemoglobin and platelet counts.
• Correlations: Serum ferritin levels showed moderate positive correlations with alanine aminotransferase (ALT) and γ-GT, and weak correlations with AST and hemoglobin.

Key Contributions

• Quantification in High-Risk Populations: The study provides large-sample quantitative evidence (n=695) delineating the prevalence of MHF specifically within the bariatric surgery candidate population, a group characterized by a high concentration of metabolic disorders.
• Multisystem Profiling: It comprehensively maps the association between MHF and multisystem pathophysiological abnormalities, extending beyond isolated hepatic or glucolipid impairments to include hematological dysfunction.
• Gender and BMI Stratification: The research highlights significant variations in MHF prevalence based on sex and BMI degree, suggesting that males and those with higher degrees of obesity are at elevated risk.
• Clinical Indicators: The identification of specific correlations, particularly the substantial elevation of γ-GT in MHF patients, offers new clinical markers for assessing the impact of iron overload on the biliary system and hepatic metabolic stress.

Significance and Claims
The authors assert that MHF is highly prevalent in patients undergoing bariatric surgery and is closely associated with systematic metabolic and hematological abnormalities. The study suggests that:

1. Risk Identification: Routine iron metabolism screening is strongly recommended for obesity management and perioperative assessment in bariatric surgery to identify high-risk subgroups.
2. Therapeutic Potential: Targeted iron regulation may serve as a promising strategy to alleviate obesity-related metabolic complications.
3. Pathophysiological Insight: The extensive systemic involvement observed suggests a common iron-dependent upstream pathophysiological pathway, potentially involving chronic inflammation, oxidative stress, or mitochondrial dysfunction.

Limitations and Modesty
The authors explicitly acknowledge that the cross-sectional design limits the ability to establish causality; the observed associations do not prove that iron overload is the etiology of the metabolic disorders, as the relationship may be bidirectional or driven by shared upstream factors. Additionally, the lack of histopathological gold standards (e.g., liver biopsy) prevents direct quantification of hepatic iron deposition, and the single-center design may limit generalizability across different ethnicities and geographic regions. Consequently, the paper frames its findings as providing critical hypotheses and clinical evidence for future investigations rather than definitive proof of causality.