Relationship of serum ferritin concentrations with metabolic cardiovascular risk factors in men without evidence for coronary artery disease

The complementary roles of iron and estrogen in menopausal differences in cardiometabolic outcomes

Biological hormonal changes are frequently cited as an explanatory factor of sex and menopause differences in cardiometabolic diseases (CMD) and its associated risk factors. However, iron metabolism which varies between sexes and among women of different reproductive stages could also play a role. Recent evidence suggest that iron may contribute to CMD risk by modulating oxidative stress pathways and inflammatory responses, offering insights into the mechanistic interplay between iron and CMD development. In the current review, we provide a critical appraisal of the existing evidence on sex and menopausal differences in CMD, discuss the pitfall of current estrogen hypothesis as sole explanation, and the emerging role of iron in CMD as complementary pathway. Prior to menopause, body iron stores are lower in females as compared to males, but the increase during and after menopause, is tandem with an increased CMD risk. Importantly, basic science experiments show that an increased iron status is related to the development of type 2 diabetes (T2D), and different cardiovascular diseases (CVD). While epidemiological studies have consistently reported associations between heme iron intake and some iron biomarkers such as ferritin and transferrin saturation with the risk of T2D, the evidence regarding their connection to CVD remains controversial. We delve into the factors contributing to this inconsistency, and the limitation of relying on observational evidence, as it does not necessarily imply causation. In conclusion, we provide recommendations for future studies on evaluating the potential role of iron in elucidating the sex and menopausal differences observed in CMD.

Optimal serum ferritin level range: iron status measure and inflammatory biomarker

This report provides perspectives concerning dual roles of serum ferritin as a measure of both iron status and inflammation. We suggest benefits of a lower range of serum ferritin as has occurred for total serum cholesterol and fasting blood glucose levels. Observations during a prospective randomized study using phlebotomy in patients with peripheral arterial disease offered unique insights into dual roles of serum ferritin both as an iron status marker and acute phase reactant. Robust positive associations between serum ferritin, interleukin 6 [IL-6], tissue necrosis factor-alpha, and high sensitivity C-reactive protein were discovered. Elevated serum ferritin and IL-6 levels associated with increased mortality and with reduced mortality at ferritin levels <100 ng mL-1. Epidemiologic studies demonstrate similar outcomes. Extremely elevated ferritin and IL-6 levels also occur in individuals with high mortality due to SARS-CoV-2 infection. Disordered iron metabolism reflected by a high range of serum ferritin level signals disease severity and outcomes. Based upon experimental and epidemiologic data, we suggest testing the hypotheses that optimal ferritin levels for cardiovascular mortality reduction range from 20 to 100 ng mL-1 with % transferrin levels from 20 to 50%, to ensure adequate iron status and that ferritin levels above 194 ng mL-1 associate with all-cause mortality in population cohorts.

Diagnostic Power of Circulatory Metabolic Biomarkers as Metabolic Syndrome Risk Predictors in Community-Dwelling Older Adults in Northwest of England (A Feasibility Study)

Background: Metabolic Syndrome (MetS) is a cluster of risk factors for diabetes and cardiovascular diseases with pathophysiology strongly linked to aging. A range of circulatory metabolic biomarkers such as inflammatory adipokines have been associated with MetS; however, the diagnostic power of these markers as MetS risk correlates in elderly has yet to be elucidated. This cross-sectional study investigated the diagnostic power of circulatory metabolic biomarkers as MetS risk correlates in older adults. Methods: Hundred community dwelling older adults (mean age: 68.7 years) were recruited in a study, where their blood pressure, body composition and Pulse Wave Velocity (PWV) were measured; and their fasting capillary and venous blood were collected. The components of the MetS; and the serum concentrations of Interleukin-6 (IL-6), Tumor Necrosis Factor-α (TNF-α), Plasminogen Activator Inhibitor-I (PAI-I), Leptin, Adiponectin, Resistin, Cystatin-C, C-Reactive Protein (CRP), insulin and ferritin were measured within the laboratory, and the HOMA1-IR and Atherogenic Index of Plasma (AIP) were calculated. Results: Apart from other markers which were related with some cardiometabolic (CM) risk, after Bonferroni correction insulin had significant association with all components of Mets and AIP. These associations also remained significant in multivariate regression. The multivariate odds ratio (OR with 95% confidence interval (CI)) showed a statistically significant association between IL-6 (OR: 1.32 (1.06–1.64)), TNF-α (OR: 1.37 (1.02–1.84)), Resistin (OR: 1.27 (1.04–1.54)) and CRP (OR: 1.29 (1.09–1.54)) with MetS risk; however, these associations were not found when the model was adjusted for age, dietary intake and adiposity. In unadjusted models, insulin was consistently statistically associated with at least two CM risk factors (OR: 1.33 (1.16–1.53)) and MetS risk (OR: 1.24 (1.12–1.37)) and in adjusted models it was found to be associated with at least two CM risk factors and MetS risk (OR: 1.87 (1.24–2.83) and OR: 1.25 (1.09–1.43)) respectively. Area under curve (AUC) for receiver operating characteristics (ROC) demonstrated a good discriminatory diagnostics power of insulin with AUC: 0.775 (0.683–0.866) and 0.785 by cross validation and bootstrapping samples for at least two CM risk factors and AUC: 0.773 (0.653–0.893) and 0.783 by cross validation and bootstrapping samples for MetS risk. This was superior to all other AUC reported from the ROC analysis of other biomarkers. Area under precision-recall curve for insulin was also superior to all other markers (0.839 and 0.586 for at least two CM risk factors and MetS, respectively). Conclusion: Fasting serum insulin concentration was statistically linked with MetS and its risk, and this link is stronger than all other biomarkers. Our ROC analysis confirmed the discriminatory diagnostic power of insulin as CM and MetS risk correlate in older adults.

Dietary iron to total energy intake ratio and type 2 diabetes incidence in a longitudinal 12-year analysis of the Korean Genome and Epidemiology Cohort Study

PURPOSE

Recent study found iron consumption has been associated with an increased risk of type 2 diabetes (T2DM). Even though, high iron intake is correlated with total caloric intake, most studies have evaluated the individual effect of iron and total caloric intake. The aim of this study was to investigate the effect of iron intake, in conjunction with total energy intake, on developing T2DM. We also investigated the interactions between dietary iron and energy ratios (IERs) and iron-related single nucleotide polymorphisms (SNPs) in the development of T2DM.

METHODS

The study was carried out in Ansan and Ansung, Korea, between March 2001 and December 2014. A total of 6413 participants (3073 men and 3340 women), aged 40-69 years, were enrolled in this study. The mean follow-up period was 8.4 years. The study population was divided into quartiles based on IERs with cut-off points at 4.54, 5.41, and 6.29. The odds ratios (ORs) for new-onset T2DM were calculated across each quartile of IERs and a random forest model was constructed using the default settings to predict new-onset T2DM. To confirm the interaction among IERs, SNPs, and the incidence of T2DM, we measured the predictive power of new-onset T2DM using IER and six SNPs in genes related to iron metabolism [rs855791 (TPMRSS6), rs38116479 (TF), rs1799852 (TF), rs2280673, rs1799945 (HFT), rs180562 (HFE)].

RESULTS

The prevalence of T2DM was 762 (11.8%). IERs showed a positive association with T2DM. The ORs were 1.30 (95% CI 1.02-1.67), 1.20 (95% CI 0.94-1.56), and 1.43 (95% CI 1.11-1.86) across the IER quartiles after adjusting for non-dietary and dietary metabolic risk factors. When the IER was 1.89-fold higher than the reference group, the risk of developing T2DM increased by 43% (OR 1.43; 95% CI 1.11-1.86).

CONCLUSION

A higher IER was positively associated with developing T2DM independent of dietary or non-dietary risk factors. We also found the possible interactions between the identified SNPs and iron intake in relations to T2DM.

Telomere Length and Oxidative Stress and Its Relation with Metabolic Syndrome Components in the Aging

A great amount of scientific evidence supports that Oxidative Stress (OxS) can contribute to telomeric attrition and also plays an important role in the development of certain age-related diseases, among them the metabolic syndrome (MetS), which is characterised by clinical and biochemical alterations such as obesity, dyslipidaemia, arterial hypertension, hyperglycaemia, and insulin resistance, all of which are considered as risk factors for type 2 diabetes mellitus (T2DM) and cardiovascular diseases, which are associated in turn with an increase of OxS. In this sense, we review scientific evidence that supports the association between OxS with telomere length (TL) dynamics and the relationship with MetS components in aging. It was analysed whether each MetS component affects the telomere length separately or if they all affect it together. Likewise, this review provides a summary of the structure and function of telomeres and telomerase, the mechanisms of telomeric DNA repair, how telomere length may influence the fate of cells or be linked to inflammation and the development of age-related diseases, and finally, how the lifestyles can affect telomere length.

Molecular Fingerprints of Iron Parameters among a Population-Based Sample

Iron deficiency is the most frequent deficiency disease and parameters of iron metabolism appear to be linked to major metabolic and cardiovascular diseases. We screened a large set of small molecules in plasma for associations with iron status among apparently healthy subjects to elucidate subclinical profiles which may provide a link between iron status and onset of diseases. Based on mass spectrometry and nuclear magnetic resonance spectroscopy we determined 613 plasma metabolites and lipoprotein subfractions among 820 apparently healthy individuals. Associations between ferritin, transferrin, haemoglobin and myoglobin and metabolite levels were tested by sex-specific linear regression analyses controlling for common confounders. Far more significant associations in women (82 out of 102) compared to men became obvious. The majority of the metabolites associated with serum ferritin and haemoglobin in women comprising fatty acid species, branched-chain amino acid catabolites and catabolites of heme. The latter was also obvious among men. Positive associations between serum transferrin and VLDL and IDL particle measures seen in women were observed in men with respect to serum ferritin. We observed a sexual-dimorphic fingerprint of surrogates of iron metabolism which may provide a link for the associations between those parameters and major metabolic and cardiovascular disease.

Impaired renal function and abnormal level of ferritin are independent risk factors of left ventricular aneurysm after acute myocardial infarction: A hospital-based case-control study

This study was performed to determine the prognostic value of glomerular filtration rate (GFR) and ferritin compromised in left ventricular aneurysm (LVA) patients who suffered acute myocardial infarction (AMI) beforehand.A hospital-based case-control study was conducted in the Department of Cardiology, First Affiliated Hospital, Zhejiang University in 2013 and 2014. Patients were divided into 3 groups according to kidney function and ferritin level. Observation outcomes include age, sex, C-reaction protein (CRP), medical history including major risk factors for CAD, ferritin and GFR, previous angina, time between MI and coronary angiography or time to rescue (TTR), and prior treatment.Around 60 patients were included in the case group (AMI with LVA) and 133 matched patients (AMI without LVA) in the control group. The prevalence of single-vessel disease (odd ratio [OR] = 2.490; 95% confidential interval [95% CI] = 1.376-4.506; P = .002), total LAD occlusion (OR = 1.897; 95% CI = 1.024-3.515; P = .041), absence of previous angina (OR = 1.930; 95% CI = 1.035-3.600; P = .037), time between myocardial infraction (MI) and coronary angiography more than 12 h (OR = 1.970; 95% CI = 1.044-3.719; P = .035), GFR less than 60 mL/min (OR = 2.933; 95% CI = 1.564-5.503; P = .001), and ferritin levels (P = .0003) were all higher in the aneurysm group compared with those in the control group. After adjustments for other variables, single-vessel disease (OR = 1.211; 95% CI = 1.080-1.342; P = .02), GFR lower than 60 mL/min (OR = 1.651; 95% CI = 1.250-2.172; P = .013), and high or low levels of ferritin (OR = 1.151; 95% CI = 1.050-1.252; P = .042) remained the independent determinants of LVA formation after AMI.Decreased GFR and abnormal ferritin levels are independent risk factors of LVA formation after AMI.

Efficacy of repeated phlebotomies in hypertriglyceridemia and iron overload: A prospective, randomized, controlled trial

BACKGROUND

High ferritin concentration is associated with hypertriglyceridemia, although it is not elucidated if iron overload has a causal role.

OBJECTIVE

To evaluate the efficacy of repeated phlebotomies in patients with iron overload and hypertriglyceridemia.

METHODS

Twelve weeks, 1:1 randomized, parallel-groups trial conducted at a University Hospital Lipid Clinic, including 86 subjects aged 18-70 years with serum ferritin >300 ng/mL in men or >200 ng/mL in women and triglycerides >200 mg/dL. Participants underwent: (1) three phlebotomies (every 3 weeks) and lipid-lowering dietary counseling or (2) lipid-lowering dietary counseling. The main outcome measured was the mean difference in percent change in triglyceride concentration between groups after the intervention. The mean differences in percent change of other clinical and biochemical variables (including cytokines and proinflammatory markers) after the intervention were also evaluated.

RESULTS

Subjects who received phlebotomies showed a significant improvement in iron metabolism. The mean percent change in triglycerides between groups was -4.68 [-20.8, 11.4]%, P = .721. Retinol-binding protein 4 decreased by 9.98 ± 21.7% after phlebotomies, with a mean percent change between groups of -14.2 [-25.8, -2.73]%, P = .017, and correlated to gamma glutamyl transferase, alanine aminotransferase and aspartate aminotransferase change. Subjects with a large reduction in hepcidin showed a large improvement in liver enzymes and proinflammatory markers.

CONCLUSIONS

A lipid-lowering diet plus a substantial reduction in iron deposits with repeated phlebotomies in subjects with hyperferritinemia and hypertriglyceridemia did not reduce triglyceride concentration in comparison with a lipid-lowering diet. Iron depletion for lipid management in these patients is not supported.

Plasma ferritin, C-reactive protein, and risk of incident type 2 diabetes in Singapore Chinese men and women

AIMS

Ferritin is postulated to be involved in diabetogenesis as a marker of iron stores. We prospectively examined the association between ferritin levels and type 2 diabetes (T2D) risk in a Chinese population.

METHODS

Plasma ferritin concentrations were assayed among 485 diabetes cases and 485 controls nested within the Singapore Chinese Health Study. Cases and controls were matched on age, gender, date of blood collection, and dialect group. Participants were free of diagnosed diabetes, cardiovascular disease, and cancer at blood collection (1999-2004). Incident self-reported T2D cases were identified at follow-up II interview (2006-2010). Multivariable conditional logistic regression models were used to compute the odds ratio (OR) and the corresponding 95% confidence intervals (CIs).

RESULTS

After adjusting for T2D risk factors, including high-sensitivity C-reactive protein (hs-CRP), adiponectin, triglycerides, HDL cholesterol and alanine aminotransferase, the OR comparing the highest versus lowest quartile of ferritin levels was 1.87 (95% CI 1.10-3.19) (P-trend=0.004). When the analysis was limited to participants with hs-CRP<1.5mg/L (below median; n=482), the OR comparing extreme quartiles of ferritin levels was 1.16 (95% CI 0.62-2.16; P-trend=0.63); while the corresponding OR was 2.51 (95% CI 1.31-4.79; P-trend<0.001) when confined to those with hs-CRP≥1.5mg/L (n=488; P-interaction=0.022). Compared to participants with both ferritin and hs-CRP levels below median, those with both levels above median had markedly increased T2D risk (P-interaction for multiplicative scale=0.037).

CONCLUSIONS

The elevation of blood ferritin levels, in the presence of raised hs-CRP, was significantly associated with increased risk of T2D.

Evaluation of the risk factors associated with rectal neuroendocrine tumors: a big data analytic study from a health screening center

BACKGROUND

Rectal neuroendocrine tumor (NET) is the most common NET in Asia. The risk factors associated with rectal NETs are unclear because of the overall low incidence rate of these tumors and the associated difficulty in conducting large epidemiological studies on rare cases. The aim of this study was to exploit the benefits of big data analytics to assess the risk factors associated with rectal NET.

METHODS

A retrospective case-control study was conducted, including 102 patients with histologically confirmed rectal NETs and 52,583 healthy controls who underwent screening colonoscopy at the Center for Health Promotion of the Samsung Medical Center in Korea between January 2002 and December 2012. Information on different risk factors was collected and logistic regression analysis applied to identify predictive factors.

RESULTS

Four factors were significantly associated with rectal NET: higher levels of cholesterol [odds ratio (OR) = 1.007, 95 % confidence interval (CI), 1.001-1.013, p = 0.016] and ferritin (OR = 1.502, 95 % CI, 1.167-1.935, p = 0.002), presence of metabolic syndrome (OR = 1.768, 95 % CI, 1.071-2.918, p = 0.026), and family history of cancer among first-degree relatives (OR = 1.664, 95 % CI, 1.019-2.718, p = 0.042).

CONCLUSION

The findings of our study demonstrate the benefits of using big data analytics for research and clinical risk factor studies. Specifically, in this study, this analytical method was applied to identify higher levels of serum cholesterol and ferritin, metabolic syndrome, and family history of cancer as factors that may explain the increasing incidence and prevalence of rectal NET.

Higher serum ferritin level and lower femur neck strength in women at the stage of bone loss (≥ 45 years of age): The Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV)

PURPOSE

Despite the clear effect of iron on bone metabolism, most clinical studies related to bone health have only focused on bone mineral density (BMD). In the present study, we investigated the relationship between serum ferritin and composite indices of femur neck strength via a population-based, cross-sectional study using the Korea National Health and Nutrition Examination Survey (KNHANES).

METHODS

Our study series included 693 women at the stage of bone loss (≥ 45 years of age), defined based on the observed patterns of age-related BMD changes in the KNHANES. Geometric bone structure properties, including hip axis length (HAL) and femur neck width (FNW), were measured using hip dual-energy X-ray absorptiometry scans and were combined with BMD, body weight, and height to create composite indices of femur neck strength relative to load in three different failure modes: compression (CSI), bending (BSI), and impact strength indices (ISI).

RESULTS

After adjustment for age, body mass index (BMI), lifestyle factors, serum 25-hydroxyvitamin D, calcium and phosphorus intake, diabetes, and menopause status, multiple regression analyses revealed that serum ferritin was inversely associated with the BMD values at the lumbar spine and femur neck, and the femur neck cortical thickness. Importantly, in all adjustment models, higher serum ferritin was consistently associated with the lower values for all three femur neck composite indices, such as CSI, BSI, and ISI.

CONCLUSIONS

These data provide the first clinical evidence that increased total body iron stores reflected by higher serum ferritin may be associated with the decrease of bone strength relative to load.

The Relationship between Serum Ferritin Levels and Insulin Resistance in Pre- and Postmenopausal Korean Women: KNHANES 2007-2010

Background

Serum ferritin levels increase in postmenopausal women, and they are reported to be linked to major health problems. Here, we investigated the association between serum ferritin levels and insulin resistance (IR) in postmenopausal women.

Methods

A total of 6632 healthy Korean women (4357 premenopausal and 2275 postmenopausal) who participated in the Korean National Health and Nutrition Examination Survey (KNHANES) in 2007–2010 were enrolled in the study. Serum ferritin values were divided into six groups for the premenopausal and postmenopausal groups. IR and obesity indices were evaluated according to the six serum ferritin groups. Statistical analysis was carried out using SAS software, version 9.2 (SAS Institute Inc., Cary, NC, USA).

Results

The association between the IR indices and ferritin groups had a higher level of statistical significance in the postmenopausal group than in the premenopausal group. In addition, for the postmenopausal group, the estimates increased significantly in the sixth ferritin group compared to those in the first ferritin group. However, the association between the obesity indices and ferritin levels was not significantly different between the premenopausal and postmenopausal groups.

Conclusion

Elevated serum ferritin levels were associated with an increased risk of insulin resistance in postmenopausal women.

Altered Concentrations of Copper, Zinc, and Iron are Associated With Increased Levels of Glycated Hemoglobin in Patients With Type 2 Diabetes Mellitus and Their First-Degree Relatives

BACKGROUND

The altered levels of some essential trace elements and antioxidant minerals have been observed in diabetic patients.

OBJECTIVES

The aim of the present study was to compare the concentrations of essential trace elements, copper (Cu), zinc (Zn), and iron (Fe) in the serum of patients who have type 2 diabetes mellitus (T2DM) with those of their non-diabetic first-degree relatives (FDR) and control subjects. The association between glycated hemoglobin (HbA1c) and levels of metals was also evaluated.

PATIENTS AND METHODS

We studied 46 subjects with T2DM, 46 FDR, and 50 control subjects matched for age and sex. Serum concentrations of Cu, Zn, and Fe were measured by colorimetric kit. Fasting blood glucose (FBG) and HbA1c were assayed using the standard kit.

RESULTS

An imbalance in the levels of the studied metals was observed in both patients with T2DM and FDR. We found significantly decreased levels of Zn and higher levels of Cu and Fe in the patients with T2DM and FDR when compared with the control subjects (P < 0.05). HbA1c levels were positively correlated with Cu and Fe and inversely correlated with Zn in the patients with T2DM and FDR (P < 0.05).

CONCLUSIONS

The patients with T2DM and FDR had altered contents of Cu, Zn, and Fe that might be a predisposing factor to the development of diabetes in future or vice versa the result of diabetes development. Impaired metabolism of these elements may contribute to the augmented risk of developing type 2 diabetes mellitus later in the life of their first-degree relatives.

Association of Serum Ferritin Levels with Metabolic Syndrome and Insulin Resistance

INTRODUCTION

The impact of CVDs and Type II DM is increasing over the last decade. It has been estimated that by 2025 their incidence will double. Ferritin is one of the key proteins regulating iron homeostasis and is a widely available clinical biomarker of iron status. Some studies suggest that prevalence of atherosclerosis and insulin resistance increases significantly with increasing serum ferritin. Metabolic syndrome is known to be associated with increased risk of atherosclerosis as well as insulin resistance.

AIM

The present study was designed to explore the association of serum ferritin levels with metabolic syndrome and insulin resistance.

MATERIALS AND METHODS

The present study was prospective, cross sectional. The study protocol was approved by IEC. The study group consisted of 90 participants (50 cases of metabolic syndrome and 40 age and sex matched controls). Diagnosis of metabolic syndrome was done as per NCEP ATP III criteria. Estimation of serum Ferritin and Insulin was done by Chemiluminescence Immunoassay (CLIA) while Glucose by Glucose Oxidase and Peroxidase (GOD-POD) method. Insulin Resistance was calculated by HOMA IR score.

STATISTICAL ANALYSIS

Data obtained was statistically analysed by using student t-test.

RESULTS

We found statistically significant rise in the levels of serum ferritin (p=<0.001), glucose (p=<0.001), insulin (p=<0.001) and HOMA IR score (p=<0.0001) in cases of metabolic syndrome as compared with controls.

CONCLUSION

High serum ferritin levels though within normal range are significantly associated with both metabolic syndrome and insulin resistance.

Relationship between Alcohol Intake and Risk Factors for Metabolic Syndrome in Men

OBJECTIVE

The precise relationship between alcohol intake and metabolic syndrome (MetS) is still unclear, and the results from previous studies have been inconclusive. Thus, we examined the effect of alcohol intake on the risk of MetS in men in order to gain more information on a potential relationship.

METHODS

This study included 22,349 men who were divided into four groups according to their average alcohol intake [non-, light (less than 20 g ethanol/day), heavy (equal or more than 20 g and less than 60 g ethanol/day) and very heavy (equal and greater than 60 g ethanol/day) drinkers]. We measured each subject's body mass index (BMI), waist circumference and blood pressure (BP) and conducted a blood test to obtain a complete blood count and biochemical panel. These results were used to obtain the MetS prevalence. Additionally, fatty liver was diagnosed using abdominal ultrasonography.

RESULTS

Light drinkers had smaller waist circumferences. Heavy and very heavy drinkers had larger waist circumferences, a higher BMI, a higher BP, higher fasting plasma glucose levels, higher triglycerides (TG) levels and higher high-density lipoprotein (HDL) cholesterol levels while they had lower low-density lipoprotein cholesterol levels than nondrinkers. The prevalence of high BP, hyperglycemia and high TG was significantly higher in heavy and very heavy drinkers than in nondrinkers. The prevalence of low HDL cholesterol levels decreased with an increase in alcohol consumption. The prevalence of MetS was significantly lower in light drinkers and higher in very heavy drinkers compared with nondrinkers.

CONCLUSION

Alcohol intake significantly influences the risk of MetS in men. A significant association was seen between an alcohol intake of 60 g/day or higher and the prevalence of MetS.

Association between levels of serum ferritin and bone mineral density in Korean premenopausal and postmenopausal women: KNHANES 2008-2010

BACKGROUND

As women go through menopause, serum estrogen decreases and ferritin increases. Decreased serum estrogen is well known to cause detrimental effects on bone health; however, data on the associations of serum ferritin with BMD before and after menopause are still lacking. Therefore, this study aimed to investigate the association between serum ferritin levels and BMD in premenopausal and postmenopausal Korean women.

METHODS

This study was performed using data from the 2008-2010 Korean National Health and Nutrition Examination Survey, including 7300 women (4229 premenopausal and 3071 postmenopausal). BMD was measured using dual X-ray absorptiometry at the femur and the lumbar spine, and serum ferritin levels were measured by chemiluminescent immunoassay.

RESULTS

Median serum ferritin levels in postmenopausal women were higher than those in premenopausal women despite the same age ranges. Serum ferritin levels were only significantly correlated with BMD on the lumbar spine (β = -0.189, p-value = 0.005) in premenopausal women after adjusting confounding factors. Additionally, BMD on the lumbar spine had tended to decrease as serum ferritin quartiles increase (P for trend = 0.035) in premenopausal women after adjusting confounding factors. On the other hand, there were no significant associations between serum ferritin levels and BMD on the total femur and, femur neck in premenopausal women, and BMD on the total femur, femur neck, and lumbar spine in postmenopausal women.

CONCLUSION

Increased serum ferritin levels were significantly associated with BMD in premenopausal women, particularly on the lumbar spine, but not in postmenopausal women.

Ferritin levels and risk of metabolic syndrome: meta-analysis of observational studies

Background

Elevated ferritin levels have been associated with single cardiovascular risk factors but the relationship to the presence of metabolic syndrome is inconclusive.

The aim of this systematic review and meta-analysis of published observational studies was to estimate the association between serum ferritin levels and metabolic syndrome in adults.

Methods

The Pubmed, SCOPUS and the Cochrane Library databases were searched for epidemiological studies that assessed the association between ferritin levels and metabolic syndrome and were published before September 2013. There were no language restrictions. Two investigators independently selected eligible studies. Measures of association were pooled by using an inverse-variance weighted random-effects model. The heterogeneity among studies was examined using the I² index. Publication bias was evaluated using the funnel plot.

Results

Twelve cross-sectional, one case–control and two prospective studies met our inclusion criteria including data from a total of 56,053 participants. The pooled odds ratio (OR) for the metabolic syndrome comparing the highest and lowest category of ferritin levels was 1.73 (95% CI: 1.54, 1.95; I² = 75,4%). Subgroup analyses indicate that pooled OR was 1.92 (95% CI: 1.61, 2.30; I² = 78%) for studies adjusting for C-reactive protein (CRP), and 1.52 (95% CI:1. 36, 1.69; I² = 41%) for studies that did not adjust for CRP (P = 0.044). This finding was remarkably robust in the sensitivity analysis. We did not find publication bias.

Conclusions

The meta-analysis suggests that increased ferritin levels are independently and positively associated with the presence of the metabolic syndrome with an odds ratio higher than 1.73.

Epidemiological associations between iron and cardiovascular disease and diabetes

Disruptions in iron homeostasis are linked to a broad spectrum of chronic conditions including cardiovascular, malignant, metabolic, and neurodegenerative disease. Evidence supporting this contention derives from a variety of analytical approaches, ranging from molecular to population-based studies. This review focuses on key epidemiological studies that assess the relationship between body iron status and chronic diseases, with particular emphasis on atherosclerosis ,metabolic syndrome and diabetes. Multiple surrogates have been used to measure body iron status, including serum ferritin, transferrin saturation, serum iron, and dietary iron intake. The lack of a uniform and standardized means of assessing body iron status has limited the precision of epidemiological associations. Intervention studies using depletion of iron to alter risk have been conducted. Genetic and molecular techniques have helped to explicate the biochemistry of iron metabolism at the molecular level. Plausible explanations for how iron contributes to the pathogenesis of these chronic diseases are beginning to be elucidated. Most evidence supports the hypothesis that excess iron contributes to chronic disease by fostering excess production of free radicals. Overall, epidemiological studies, reinforced by basic science experiments, provide a strong line of evidence supporting the association between iron and elevated risk of cardiovascular disease and diabetes. In this narrative review we attempt to condense the information from existing literature on this topic.

Iron, human growth, and the global epidemic of obesity

Iron is an essential nutrient utilized in almost every aspect of cell function and its availability has previously limited life. Those same properties which allow iron to function as a catalyst in the reactions of life also present a threat via generation of oxygen-based free radicals. Accordingly; life exists at the interface of iron-deficiency and iron-sufficiency. We propose that: (1) human life is no longer positioned at the limits of iron availability following several decades of fortification and supplementation and there is now an overabundance of the metal among individuals of many societies; (2) this increased iron availability exerts a positive effect on growth by targeting molecules critical in regulating the progression of the cell cycle; there is increased growth in humans provided greater amounts of this metal; and indices of obesity can positively correlate with body stores of iron; and (3) diseases of obesity reflect this over-abundance of iron. Testing potential associations between iron availability and both obesity and obesity-related diseases in populations will be difficult since fortification and supplementation is so extensively practiced.

The association between higher serum ferritin level and lower bone mineral density is prominent in women ≥45 years of age (KNHANES 2008-2010)

SUMMARY

Data gathered from a nationally representative cohort demonstrate that higher serum ferritin levels are significantly associated with lower bone mass at various skeletal sites and the increased prevalence of osteoporosis and fractures, especially in women ≥45 years of age.

INTRODUCTION

Despite extensive in vitro and in vivo studies showing the detrimental effects of iron on bone metabolism, the clinical studies relating to osteoporosis-related phenotypes have not been evaluated extensively. In the present study, we investigated and compared the association between serum ferritin and bone mineral density (BMD), depending on the stratified age groups in both genders.

METHODS

This is a population-based, cross-sectional study from the Korea National Health and Nutrition Examination Surveys, including 14,017 Koreans (6,817 men and 7,200 women) aged 10-80 years. BMD was measured using dual X-ray absorptiometry, and osteoporosis was diagnosed by the World Health Organization definition.

RESULTS

Initially, we divided the subjects into three age groups, based on the patterns of age-related BMD changes in this national cohort (i.e., ≤24, 25-44, and ≥45 years old). Serum ferritin concentrations were inversely associated with BMD values at all measured sites after adjustment for confounders, only in women ≥45 years of age (P = 0.041 to <0.001). Furthermore, when we divided these women into serum ferritin quartiles, the odds for prevalent osteoporosis and fractures were 1.55-fold (95 % CI = 1.09-2.23) and 1.52-fold (95 % CI = 1.02-2.27) higher, respectively, in subjects in the highest quartile compared with those in the lowest quartile.

CONCLUSIONS

These results provide the first clinical evidence that the associations between serum ferritin level and bone parameters could be the most prominent in women ≥45 years of age.

Association between serum ferritin levels and risk of the metabolic syndrome in Chinese adults: a population study

Ferritin is a ubiquitous intracellular protein that can store and release iron and act as a buffer against iron deficiency and iron overload. Ferritin is widely used as a clinical biomarker to evaluate iron status. Increased serum ferritin concentrations have been reported to be associated with metabolic syndrome (MetS) features. However, serum ferritin concentrations differ significantly according to sex and ethnicity, and the data concerning the relationship between serum ferritin concentrations and MetS in Asian men and women are conflicting. This study aimed to explore the relationship between serum ferritin and MetS in Chinese population. Fasting blood samples and anthropometric data collected on 8,441 adults aged 18 and older in 2009 as part of the China Health and Nutrition Survey, a large-scale longitudinal, household-based survey in China. Data was collected by trained physicians and biomarkers were measured with Hitachi Clinical Autoanalyzer 7600 D model and P model. Median levels of serum ferritin were significantly higher in men compared with women (121.9 vs. 51.0 ng/ml, P < 0.001), and significantly lower in non metabolic syndrome population with MetS population (73.2 vs. 106.0 ng/ml, P < 0.001). The difference remained significant after further adjusted for age, nationality, Body mass index (BMI), smoking status, and alcohol consumption. For both men and women, the highest prevalence of MetS occurred in the highest quartile of serum ferritin. The odds ratios increased progressively across the ferritin quartiles (P<0.001 for trend). Increased serum ferritin concentrations are associated with the metabolic syndrome among men and women in China.

Lipoprotein(a), ferritin, and albumin in acute phase reaction predicts severity and mortality of acute ischemic stroke in North Indian Patients

BACKGROUND

Inflammation plays a crucial role in the pathogenesis and prognosis of stroke. We studied the behavior of lipoprotein(a) [Lp(a)], ferritin, and albumin as acute phase reactants and their roles in the severity and mortality of stroke.

METHODS

We recruited 100 consecutive patients with acute ischemic stroke and 120 controls. Blood samples were drawn on days 1 and 7 and at both 3 and 6 months. Stroke was classified using Trial of Org 10172 in Acute Stroke Treatment classification. Stroke severity was assessed using the National Institutes of Health Stroke Scale. Prognosis at 6 months was assessed using the modified Rankin Scale, and mortality was assessed using the Kaplan-Meier analysis. Serum levels of interleukin-6 (IL-6), Lp(a), ferritin, and albumin were measured using enzyme-linked immunosorbent assay, immunoturbidimetry, and chemiluminescence commercial kits, respectively.

RESULTS

Levels of IL-6, Lp(a), and ferritin were consistently higher among cases than controls (P < .0001). Serum Lp(a) levels peaked at day 7 after stroke and tapered thereafter. Albumin levels were lower than controls on admission day and increased subsequently. In our study, Lp(a) acted as an acute phase reactant while albumin acted as a negative acute phase reactant. There was no association between Trial of Org 10172 in Acute Stroke Treatment subtype and elevated serum levels of Lp(a), albumin, and ferritin. Lp(a) and ferritin were high in patients with severe stroke. Albumin was negatively correlated with stroke severity. Serum levels of Lp(a) ≥ 77 mg/dL, albumin ≤ 3.5 g/dL, and ferritin ≥ 370 ng/dL is associated with a significantly increased risk of having a poorer outcome in stroke. Serum levels of Lp(a) >77 mg/dL and albumin <3.5 g/dL were also associated with increased mortality.

CONCLUSIONS

High levels of Lp(a) and ferritin and low levels of albumin are associated with increased severity and poorer long term prognosis of stroke. Patients with admission levels of Lp(a) >77 mg/dL and albumin <3.5 g/dL had increased mortality.

Association of serum ferritin and the development of metabolic syndrome in middle-aged Korean men: a 5-year follow-up study

OBJECTIVE

Elevated serum ferritin has been known to be associated with the prevalence of metabolic syndrome (MetS). However, there was no research to examine whether serum ferritin levels have been actually associated with the prospective development of MetS. Accordingly, we carried out a prospective study to evaluate the longitudinal effects of baseline serum ferritin levels on the development of MetS.

RESEARCH DESIGN AND METHODS

A MetS-free cohort of 18,022 healthy Korean men, who had participated in a medical health checkup program in 2005, was followed until 2010. MetS was defined according to the joint interim statement of the International Diabetes Federation Task Force on Epidemiology and Prevention. Cox proportional hazards models were performed.

RESULTS

During 45,919.3 person-years of follow-up, 2,127 incident cases of MetS developed between 2006 and 2010. After adjusting for multiple covariates, the hazard ratios (95% CI) for incident MetS comparing the second quintile to the fifth quintile of serum ferritin levels versus the first quintile were 1.19 (0.98-1.45), 1.17 (0.96-1.43), 1.36 (1.12-1.65), and 1.66 (1.38-2.01), respectively (P for trend <0.001). These associations were apparent in the clinically relevant subgroup analyses.

CONCLUSIONS

Elevated serum ferritin levels were independently associated with future development of MetS during the 5-year follow-up period.

Iron overload accelerates bone loss in healthy postmenopausal women and middle-aged men: a 3-year retrospective longitudinal study

Despite extensive experimental and animal evidence about the detrimental effects of iron and its overload on bone metabolism, there have been no clinical studies relating iron stores to bone loss, especially in nonpathologic conditions. In the present study, we performed a large longitudinal study to evaluate serum ferritin concentrations in relation to annualized changes in bone mineral density (BMD) in healthy Koreans. A total of 1729 subjects (940 postmenopausal women and 789 middle-aged men) aged 40 years or older who had undergone comprehensive routine health examinations with an average 3 years of follow-up were enrolled. BMD in proximal femur sites (ie, the total femur, femur neck, and trochanter) was measured with dual-energy X-ray absorptiometry using the same equipment at baseline and follow-up. The mean age of women and men in this study was 55.8 ± 6.0 years and 55.5 ± 7.8 years, respectively, and serum ferritin levels were significantly higher in men than in women (p < 0.001). The overall mean annualized rates of bone loss in the total femur, femur neck, and trochanter were -1.14%/year, -1.17%/year, and -1.51%/year, respectively, in women, and -0.27%/year, -0.34%/year, and -0.41%/year, respectively, in men. After adjustment for potential confounders, the rates of bone loss in all proximal femur sites in both genders were significantly accelerated in a dose-response fashion across increasing ferritin quartile categories (p for trend = 0.043 to <0.001). Consistently, compared with subjects in the lowest ferritin quartile category, those in the third and/or highest ferritin quartile category showed significantly faster bone loss in the total femur and femur neck in both genders (p = 0.023 to <0.001). In conclusion, these data provide the first clinical evidence that increased total body iron stores could be an independent risk factor for accelerated bone loss, even in healthy populations.

Body iron stores and risk of type 2 diabetes: results from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam study

AIMS/HYPOTHESIS

The aim of this study was to prospectively examine the association between body iron stores and risk of type 2 diabetes.

METHODS

We designed a case-cohort study among 27,548 individuals within the population-based European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam study. During 7 years of follow-up, 849 incident cases of type 2 diabetes were identified. Of these, 607 remained for analyses after exclusion of participants with missing data or abnormal glucose levels at baseline. A sub-cohort of 2,500 individuals was randomly selected from the full cohort, comprising 1,969 individuals after applying the same exclusion criteria.

RESULTS

After adjustment for age, sex, BMI, waist circumference, sports activity, bicycling, education, occupational activity, smoking habit, alcohol consumption and circulating levels of γ-glutamyltransferase, alanine aminotransferase, fetuin-A, high-sensitivity C-reactive protein, adiponectin, HDL-cholesterol and triacylglycerol, higher serum ferritin concentrations were associated with a higher risk of type 2 diabetes (RR in the highest vs lowest quintile, 1.73; 95% CI 1.15, 2.61; p(trend) = 0.002). No significant association was observed for soluble transferrin receptor (RR 1.33; 95% CI 0.85, 2.09; p(trend) = 0.50). The soluble transferrin receptor-to-ferritin ratio was significantly inversely related to risk (RR 0.61; 95% CI 0.41, 0.91; p(trend) = 0.02).

CONCLUSIONS/INTERPRETATION

High ferritin levels are associated with higher risk of type 2 diabetes independently of established diabetes risk factors and a range of diabetes biomarkers whereas soluble transferrin receptor concentrations are not related to risk. These results support the hypothesis that higher iron stores below the level of haemochromatosis are associated with risk of type 2 diabetes.

High serum ferritin levels are associated with metabolic risk factors in non-obese Korean young adults: Korean National Health and Nutrition Examination Survey (KNHANES) IV

OBJECTIVE

The purpose of this study is to investigate the relationship between serum ferritin levels and metabolic risk factors in nonobese Korean young adults.

DESIGN AND SUBJECTS

We analysed the fourth annual Korea National Health and Nutrition Examination Survey (KNHANES) in young adults (aged 19-39 years), conducted between 2007 and 2008. A total of 1542 nonobese [body mass index (BMI) <25 kg/m(2) ] young adults (684 men and 858 women) were enrolled. Using blood pressure and levels of serum triglycerides, plasma glucose and high-density lipoprotein (HDL) cholesterol, the Asian criteria for abdominal obesity (Waist circumference ≥90 cm in men or ≥80 cm in women) was used to identify individuals with metabolic syndrome.

MEASUREMENTS

Data on anthropometry, fasting plasma glucose, insulin, lipid profile and ferritin levels were analysed.

RESULTS

The prevalence of metabolic syndrome was 4·1% for men and 2·7% for women. High fasting glucose and the prevalence of metabolic syndrome increased progressively across three different tertiles of ferritin levels in men. However, high ferritin levels were associated with high triglycerides, low HDL cholesterol and metabolic syndrome in women. After adjustment for age, smoking, alcohol consumption, BMI and ALT levels, low HDL cholesterol (OR 1·66, 95% confidence interval (CI) 1·16-2·36) and the presence of metabolic syndrome (OR 3·87, 95% CI 1·34-11·2) were independently associated with high serum ferritin levels in Korean nonobese young women.

CONCLUSIONS

Our results suggest that elevated serum ferritin levels may be employed as a marker of metabolic syndrome in nonobese young adult women.

Serum ferritin level is associated with the prevalence of metabolic syndrome in Korean adults: the 2007-2008 Korean National Health and Nutrition Examination Survey

BACKGROUND

Increased ferritin concentrations, which reflect body iron stores, contribute to insulin dysfunction and metabolic syndrome (MetS).

METHODS

This cross-sectional study included 7346 subjects (3229 men and 4117 women) who participated in the 2007-2008 Korean National Health and Nutrition Examination Survey (KNHANES). We adopted the modified Asian criteria for MetS from the American Heart Association/National Heart, Lung, and Blood Institute.

RESULTS

In comparison with participants in the first serum ferritin quartile, the odds ratio (95% confidence interval) for MetS for participants in the fourth serum ferritin quartile was 1.67 (1.24-2.23) in men and 1.41 (1.06-1.88) in women after adjusting for multiple covariates (including menopausal status in women) except insulin resistance. This association was attenuated, however, after additionally adjusting for insulin resistance [1.46 (1.08-1.98) in men and 1.22 (0.91-1.65) in women]. In particular, higher serum ferritin concentrations were associated with increased triglyceride concentrations in men and glucose intolerance in women.

CONCLUSIONS

Increased serum ferritin level was positively associated with the prevalence of MetS and with some diagnostic components of MetS, i.e., we found that increased serum ferritin concentrations were associated with high triglyceride and glucose concentrations in men and women, respectively.

Association of serum ferritin with metabolic syndrome and diabetes mellitus in the South Korean general population according to the Korean National Health and Nutrition Examination Survey 2008

We examined the association of serum ferritin levels with metabolic syndrome (MS) and diabetes mellitus in a representative sample of the adult South Korean population using data from the 2008 Korean National Health and Nutrition Examination Survey. We conducted a cross-sectional study of 6311 adults older than 20 years who participated in the 2008 Korean National Health and Nutrition Examination Survey. Metabolic syndrome was defined as the presence of at least 3 of the following: elevated blood pressure, low high-density lipoprotein cholesterol, elevated serum triglycerides, elevated plasma glucose, and abdominal obesity. Diabetes mellitus was defined as fasting glucose of at least 126 mg/dL. Insulin resistance was determined using the homeostasis model assessment estimate of insulin resistance. In a representative sample of the adult Korean population, MS was more prevalent in the highest quartile compared with the lowest quartile of serum ferritin concentrations in women following adjustments for age, education, smoking, alcohol intake, body mass index, aspartate aminotransferase, and alanine aminotransferase. Diabetes mellitus was more prevalent in the highest quartile compared with the lowest quartile of serum ferritin concentrations in premenopausal women and men. The geometric means of fasting insulin and insulin resistance determined using the homeostasis model assessment of insulin resistance in the fourth serum ferritin quartiles of postmenopausal women and men were significantly higher compared with those in the first quartile of the respective groups. The present study demonstrates that elevated serum ferritin concentrations are associated with an increased risk of MS and diabetes mellitus in a representative sample of the adult South Korean population.

The relationship between serum ferritin and metabolic syndrome in healthy Korean men

BACKGROUND AND OBJECTIVE

Elevated serum ferritin levels have been reported to be associated with several metabolic disorders. We investigated the relationship between serum ferritin level and metabolic syndrome and its components in healthy Korean men.

METHODS

In this cross-sectional study, serum ferritin level and metabolic syndrome and its components were measured from 18 581 men from January to December in 2008. The presence of metabolic syndrome was determined according to the most recent consensus report of the National Cholesterol Education Program's Third Adult Treatment Panel. Logistic regression models were applied to examine the relationship between the serum ferritin level and the metabolic syndrome and its components.

RESULTS

After adjusting for clinical covariates, the odds ratio and 95% confidence intervals of metabolic syndrome with respect to Q2, Q3 and Q4 were 1.34 (1.14-1.57), 1.49 (1.24-1.70) and 1.99 (1.70-2.33), respectively (p for trend < 0.001). The multivariable-adjusted model also showed a significantly graded relationship between individual components of metabolic syndrome and the quartile groups of serum ferritin.

CONCLUSIONS

In this study, elevated ferritin concentration is independently associated with metabolic syndrome and its components among healthy Korean men.

Increased oxidative stress and iron overload in Jordanian β-thalassemic children

β-Thalassemia (β-thal) is associated with abnormal synthesis of hemoglobin (Hb). Repeated blood transfusions in patients with β-thal major (β-TM) leads to an enhanced generation of reactive oxygen species (ROS), and subjects patients to peroxidative injury. We studied the antioxidant status and oxidative damage to children with β-thal in Jordan. Samples from 40 children with β-thal and 40 healthy controls were used. All children were under 13 years of age. Our results showed that plasma thiobarbituric acid reactive substances (TBARS) were elevated in β-thalassemic children compared to controls together with compensatory increase in superoxide dismutase (SOD) activity and decrease in catalase (CAT) activity. Elevated serum ferritin showed positive correlation with elevated liver enzyme levels except gamma glutamyl transferase (GGT), confirming liver involvement due to iron overload. Serum ferritin also showed a positive correlation with elevated TBARS and SOD, suggesting that iron overload is involved in the oxidative stress shown in cells.

The role of the inflammatory markers ferritin, transferrin and fibrinogen in the relationship between major depression and cardiovascular disorders - The German Health Interview and Examination Survey

OBJECTIVE

To determine levels of inflammation (ferritin, transferrin and fibrinogen) in major depression (MDD) and comorbid cardiovascular disease (CVD) in an adult population.

METHOD

In 4181 participants of the German Health Interview and Examination Survey MDD was assessed through the Composite International Diagnostic Interview (CIDI). Coronary heart disease, stroke, and hypertension were diagnosed by a computer-assisted physician interview. Analyses were performed using anova models stratified for gender.

RESULTS

Ferritin, transferrin and fibrinogen levels showed opposing patterns in individuals with either CVD or MDD alone. In comorbidity analyses, male participants with MDD plus comorbid CHD or hypertension had lower levels of ferritin and lower fibrinogen levels in hypertension compared to men without MDD, while in women, results were inconsistent.

CONCLUSION

Opposing patterns of inflammatory markers in CVD or MDD alone were reversed when both conditions were present. MDD reduced levels of ferritin, transferrin and fibrinogen in CVD in a gender-specific way.

Biomarkers of body iron stores and risk of developing type 2 diabetes

AIM

Iron may contribute to the pathogenesis of type 2 diabetes mellitus (DM) by inducing oxidative stress and interfering with insulin secretion. Elevated ferritin levels are associated with increased DM risk among healthy individuals. However, it is yet unknown if ferritin predicts DM incidence among high-risk individuals with impaired glucose tolerance (IGT). Furthermore, the association between soluble transferrin receptors (sTfR), a novel marker of iron status, and DM risk has not yet been prospectively investigated in these individuals. We conducted this study to evaluate the association between baseline levels of ferritin and sTfR and the risk of developing DM among overweight and obese individuals at high risk of DM.

METHODS

This nested case-control study (280 cases and 280 matched controls) was conducted within the placebo arm of the Diabetes Prevention Program, is a clinical trial conducted among overweight/obese individuals with IGT. Ferritin and sTfR levels were measured by immunoturbidimetric assays. Incident DM was ascertained by annual 75-g oral glucose tolerance test and semi-annual fasting glucose.

RESULTS

Compared with controls, cases had higher sTfR levels (3.50 +/- 0.07 vs. 3.30 +/- 0.06 mg/l; p = 0.03), but ferritin levels were not statistically different. The multivariable odds ratios (OR) and 95% confidence intervals (95% CI) for DM incidence comparing highest with the lowest quartiles of sTfR was 2.26 (1.37-4.01) (p-trend: 0.008).

CONCLUSIONS

Modestly elevated sTfR levels are associated with increased DM risk among overweight and obese individuals with IGT. Future studies should evaluate factors determining sTfR levels and examine if interventions that lower body iron stores reduce DM incidence.

The long-term impact of ferritin level on treatment and complications of type 2 diabetes

AIM

To investigate if high-serum ferritin has long-term impact on response to treatment and the development of diabetic complications in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

We analysed the record of 90 consecutive type 2 diabetic subjects who had serum ferritin level determined soon after diagnosis of diabetes and who also had long-term follow-up data.

RESULTS

Patients with higher serum ferritin level had slightly worse triglyceride, blood pressure and liver enzyme levels at the end of follow up. However, ferritin level had no impact on the initial or final requirements for diabetic medication and the development of diabetic complications.

CONCLUSIONS

Although elevated serum ferritin is a marker of insulin resistance and chronic inflammation, it is not necessarily a bad prognostic indicator that should affect the clinician's approach to management.

[Serum ferritin and risk of the metabolic syndrome in some Korean rural residents]

OBJECTIVES

The purpose of this study was to examine the relationship between serum ferritin and the metabolic syndrome (MS).

METHODS

We conducted a cross-sectional study of 1,444 adults over age 40 and under age 70 that lived in a rural area and participated in a survey conducted as part of the Korean Rural Genomic Cohort Study (KRGCS). The MS was defined as the presence of at least three of the followings: elevated blood pressure, low high density lipoprotein cholesterol, elevated serum triglycerides, elevated plasma glucose, or abdominal obesity. After adjustment for age, alcohol intake, menopausal status, body mass index (BMI), high sensitivity C-reactive protein (hs-CRP), and alanine aminotransferase (ALT), odds ratios (ORs) for the prevalence of the MS by sex were calculated for quartiles of serum ferritin using logistic regression analysis.

RESULTS

The MS was more common in those persons with the highest levels of serum ferritin, compared to persons with the lowest levels, in men (37.1% vs. 22.4%, p=0.006) and women (58.8% vs. 34.8, p<0.001). In both sexes, the greater the number of MS components presents, the greater the serum ferritin levels. After adjustment for age, alcohol intake, and menopausal status, the OR for metabolic syndrome, comparing the fourth quartile of ferritin with the first quartile, was 2.21 (95% confidence interval; CI=1.26-3.87; p-trend=0.024) in men and 2.10 (95% CI=1.40-3.17; p-trend=0.001) in women. However, after further adjustment for BMI, hs-CRP, and ALT, the ORs were statistically attenuated in both sexes.

CONCLUSIONS

Moderately elevated serum ferritin levels were not independently associated with the prevalence of the MS after adjusting for other risk factors. Further studies are needed to obtain evidence concerning the association between serum ferritin levels and the MS.

The role of iron in type 2 diabetes in humans

The role of micronutrients in the etiology of type 2 diabetes is not well established. Several lines of evidence suggest that iron play may a role in the pathogenesis of type 2 diabetes. Iron is a strong pro-oxidant and high body iron levels are associated with increased level of oxidative stress that may elevate the risk of type 2 diabetes. Several epidemiological studies have reported a positive association between high body iron stores, as measured by circulating ferritin level, and the risk of type 2 diabetes and of other insulin resistant states such as the metabolic syndrome, gestational diabetes and polycystic ovarian syndrome. In addition, increased dietary intake of iron, especially that of heme iron, is associated with risk of type 2 diabetes in apparently healthy populations. Results from studies that have evaluated the association between genetic mutations related to iron metabolism have been inconsistent. Further, several clinical trials have suggested that phlebotomy induced reduction in body iron levels may improve insulin sensitivity in humans. However, no interventional studies have yet directly evaluated the effect of reducing iron intake or body iron levels on the risk of developing type 2 diabetes. Such studies are required to prove the causal relationship between moderate iron overload and diabetes risk.

Relationship between indices of iron status and coronary risk factors including diabetes and the metabolic syndrome in Saudi subjects without overt coronary disease

There have been inconsistent reports on the relationship between iron status and coronary artery diseases (CAD), and little data on this relationship in non-Caucasian populations. We assessed dietary iron by questionnaire and measured serum iron and ferritin levels in 270 Saudi male subjects without established CAD, 130 of whom were angiogram negative. Serum lipid profile, glucose, high sensitivity-C reactive protein (hs-CRP), serum soluble intercellular adhesion molecules-1 (sICAM-1), and caeruloplasmin were measured in all subjects. The angiogram negative patients, had lower serum ferritin (p<0.05) and iron (p<0.0001) levels than the 140 subjects without reported cardiovascular diseases (CVD). Serum iron correlated with serum triglycerides (p<0.0001) and total cholesterol (p<0.05) levels for this latter group and the groups combined. Serum ferritin correlated with serum total cholesterol and low-density lipoprotein (LDL)-cholesterol in the combined group (p<0.05), and was correlated with blood glucose and serum LDL-cholesterol (p<0.05) in the subjects without reported CVD. After adjustment for confounding variables, serum iron levels remained a significant correlate with total calorie intake and serum triglycerides. Serum ferritin also correlated significantly with cholesterol intake and fasting serum total cholesterol. Dietary iron was significantly related to dietary cholesterol and fiber, age, smoking habits, and serum total cholesterol level. Hence, indices of iron status were related to several coronary risk factors in the Saudi population.

On risks and benefits of iron supplementation recommendations for iron intake revisited

Iron is an essential trace element with a high prevalence of deficiency in infants and in women of reproductive age from developing countries. Iron deficiency is frequently associated with anaemia and, thus, with reduced working capacity and impaired intellectual development. Moreover, the risk for premature delivery, stillbirth and impaired host-defence is increased in iron deficiency. Iron-absorption and -distribution are homeostatically regulated to reduce the risk for deficiency and overload. These mechanisms interact, in part, with the mechanisms of oxidative stress and inflammation and with iron availability to pathogens. In the plasma, fractions of iron may not be bound to transferrin and are hypothesised to participate in atherogenesis. Repleted iron stores and preceding high iron intakes reduce intestinal iron absorption which, however, offers no reliable protection against oral iron overload. Recommendations for dietary iron intake at different life stages are given by the US Food and Nutrition Board (FNB), by FAO/WHO and by the EU Scientific Committee, among others. They are based, on estimates for iron-losses, iron-bioavailability from the diet, and iron-requirements for metabolism and growth. Differences in choice and interpretation of these estimates lead to different recommendations by the different panels which are discussed in detail. Assessment of iron-related risks is based on reports of adverse health effects which were used in the attempts to derive an upper safe level for dietary iron intake. Iron-related harm can be due to direct intestinal damage, to oxidative stress, or to stimulated growth of pathogens. Unfortunately, it is problematic to derive a reproducible cause-effect and dose-response relationship for adverse health effects that suggest a relationship to iron-intake, be they based on mechanistic or epidemiological observations. Corresponding data and interpretations are discussed for the intestinal lumen, the vascular system and for the intracellular and interstitial space, considering interference of the mechanisms of iron homoeostasis as a likely explanation for differences in epidemiological observations.

Serum ferritin, cardiovascular risk factors and ischaemic heart diseases: a prospective analysis in the SU.VI.MAX (SUpplementation en VItamines et Minéraux AntioXydants) cohort

BACKGROUND

Iron has been suggested to play a role in the development of cardiovascular disease (CVD) through its pro-oxidant properties. However, epidemiological studies on iron status and the risk of CVD have yielded conflicting results. We therefore carried out a prospective study to evaluate the relationship between iron status and CVD in a middle-aged French population.

METHODS

In total, 9917 subjects (3223 men aged 45-60 years and 6694 women aged 35-60 years) included in the SU.VI.MAX (SUpplementation en VItamines et Minéraux AntioXydants) cohort were followed prospectively for 7.5 years. All cases of ischaemic heart disease (IHD) were identified and validated. CVD risk factors, haemoglobin and serum ferritin concentrations were measured at baseline.

FINDINGS

Of men 4.3%, and of women 37.8%, presented at baseline a serum ferritin concentration <30 microg l(-1). During the follow-up, 187 subjects (148 men, 39 women) developed IHD. Serum ferritin was positively associated with total cholesterol, serum triglycerides, systolic and diastolic blood pressure, body mass index and haemoglobin. No linear association was found between serum ferritin and IHD risk in men or in women.

CONCLUSION

Our data do not support a major role of iron status in the development of IHD in a healthy general population.

Iron intake and the risk of type 2 diabetes in women: a prospective cohort study

OBJECTIVE

Epidemiological studies suggest that high body iron stores are associated with insulin resistance and type 2 diabetes. The aim of this study was to evaluate the association between dietary intake of iron and the risk of type 2 diabetes.

RESEARCH DESIGN AND METHODS

We conducted a prospective cohort study within the Nurses' Health Study. We followed 85,031 healthy women aged 34-59 years from 1980 to 2000. Dietary data were collected every 4 years, and data on medical history and lifestyle factors were updated biennially.

RESULTS

During the 20 years of follow-up, we documented 4,599 incident cases of type 2 diabetes. We found no association between total, dietary, supplemental, or nonheme iron and the risk of type 2 diabetes. However, heme iron intake (derived from animal products) was positively associated with risk; relative risks (RRs) across increasing quintiles of cumulative intake were 1.00, 1.08 (95% CI 0.97-1.19), 1.20 (1.09-1.33), 1.27 (1.14-1.41), and 1.28 (1.14-1.45) (P(trend) < 0.0001) after controlling for age, BMI, and other nondietary and dietary risk factors. In addition, when we modeled heme iron in seven categories, the multivariate RR comparing women who consumed > or =2.25 mg/day and those with intake <0.75 mg/day was 1.52 (1.22-1.88). The association between heme iron and the risk of diabetes was significant in both overweight and lean women.

CONCLUSIONS

This large cohort study suggests that higher heme iron intake is associated with a significantly increased risk of type 2 diabetes.

[Iron overload and insulin resistance]

There is increasing evidence that moderately elevated body iron stores, below levels commonly found in genetic hemochromatosis, may be associated with adverse health outcomes. Genetic hemochromatosis, characterized by transferrin saturation (TS) greater than 45%, is most often linked to homozygosity of the HFE C282Y allele. The phenotype is also modulated by mutations of more recently discovered genes (including ferroportin, hemojuvelin, hepcidin, and transferrin receptor) and environmental factors (including alcohol, viruses, diet, blood loss). Iron overload without hemochromatosis is characterized by high levels of serum ferritin and normal TS, as seen in dysmetabolic hepatosiderosis. Elevated serum ferritin levels predict incident type 2 diabetes in prospective studies and have been associated with hypertension, dyslipidemia, glucose tolerance disturbances, central adiposity, and metabolic syndrome. High ferritin levels are not synonymous with iron overload and may in some cases be a simple marker of insulin resistance.

Serum ferritin and risk of the metabolic syndrome in U.S. adults

OBJECTIVE

We examined the relationship among iron stores, the metabolic syndrome, and insulin resistance.

RESEARCH DESIGN AND METHODS

We conducted a cross-sectional study of 6,044 adults >20 years of age who participated in the Third National Health and Nutrition Examination Survey. Metabolic syndrome was defined as the presence of at least three of the following: elevated blood pressure, low HDL cholesterol, elevated serum triglycerides, elevated plasma glucose, and abdominal obesity. Insulin resistance was estimated using homeostasis model assessment (for insulin resistance), fasting insulin, and triglyceride-to-HDL cholesterol ratio.

RESULTS

After excluding individuals with likely hemochromatosis, mean serum ferritin values in premenopausal women, postmenopausal women, and men were 33.6, 93.4, and 139.9 microg/l, respectively. Metabolic syndrome was more common in those with the highest compared with the lowest levels of serum ferritin in premenopausal women (14.9 vs. 6.4%, P = 0.002), postmenopausal women (47.5 vs. 28.2%, P < 0.001), and men (27.3 vs. 13.8%, P < 0.001). Insulin resistance also increased across quartiles of serum ferritin for men and postmenopausal women and persisted after adjustment for age, race/ethnicity, C-reactive protein, smoking, alcohol intake, and BMI.

CONCLUSIONS

Elevated iron stores were positively associated with the prevalence of the metabolic syndrome and with insulin resistance.

Oxidant, antioxidant status and metabolic data in patients with beta-thalassemia

BACKGROUND

In beta-thalassemia major impaired biosynthesis of beta globin leads to accumulation of unpaired alpha globin chain. An iron overload, usually observed, generates oxygen-free radicals and peroxidative tissue injury.

AIM

To investigate hematological parameters, oxidative stress and the antioxidant capacity in beta-thalassemia patients compared to control subjects in order to determine their impact in several organs functions.

METHODS

This study was conducted on 56 beta-thalassemia major patients compared to 51 healthy subjects. We determined metabolic parameters (glycaemia, lipid parameters, electrolytes, iron indices, hepatic, renal and heart functions tests), plasmatic thiobarbituric acid reactive substances (TBARS), plasmatic peroxyl radical trapping potential (TRAP), plasmatic superoxide dismutase (SOD), erythrocyte gluthathione peroxidase (GPX), plasmatic vitamin E, vitamin A and trace elements.

RESULTS

Except triglycerides, lipid fractions were significantly decreased in beta-thalassemia compared to controls. Serum ferritin, iron, TBARS concentrations, SOD and GPX activities were significantly increased. But TRAP, vitamin E and zinc concentrations were significantly decreased.

CONCLUSION

Our findings confirm the peroxidative status generated by iron overload in beta-thalassemia major patients and highlight the rapid formation of marked amounts of TBARS and the increase of SOD and GPX activity. Our study suggested that in beta-thalassemia the first organ impaired is the liver.

Relationship of serum ferritin with cardiovascular risk factors and inflammation in young men and women

Elevated ferritin levels have been reported as a risk factor for coronary heart disease in Finnish and Italian studies. Studies in other populations have found no association between ferritin and cardiovascular disease raising the possibility of confounding with other cardiovascular risk factors. We determined ferritin levels, metabolic cardiovascular risk factors, C-reactive protein (CRP), anthropometric measurements and blood pressure in 815 men and women aged 26 years. In women serum ferritin correlated with CRP, waist measurement, body mass index (BMI), and triglycerides. In multiple regression analysis CRP alone was independently associated with serum ferritin. Serum ferritin in men correlated with waist measurement, BMI, triglycerides and high-density lipoprotein (HDL) cholesterol. After adjustment for the other variables, waist measurement was the only independent predictor of ferritin. Ferritin levels in young men and women are associated with obesity and serum triglycerides, HDL cholesterol in men and inflammation in women. Confounding may contribute to reports of associations between ferritin and cardiovascular disease.

Hypotransferrinemia of chronically hemodialyzed patients

Increasingly, the iron needs of hemodialysis patients receiving erythropoietin are being met by infusions of intravenous iron guided by laboratory tests to measure body iron availability. The interpretation of assays based on ferritin and transferrin must take into account the effect of inflammation on both proteins and malnutrition on the latter. In our chronic hemodialysis population, hypotransferrinemia was present in greater than 90% of the patients. Using statistical methods and laboratory studies, we sought to identify the principal reasons for the high prevalence of hypotransferrinemia. We observed that transferrin levels were disproportionately low relative to albumin and prealbumin and correlated inversely with ferritin levels. There was no correlation between transferrin and the soluble transferrin receptor. After the infusion of 900 mg of iron, transferrin saturation increased and total transferrin decreased so that unsaturated iron bonding capacity decreased as well. Ferritin concentrations increased significantly after iron loading. Attempts to demonstrate activation of the patients' antioxidant mechanisms associated with iron infusion were negative. We concluded that the low transferrin may be principally the result of diminished synthesis related to the chronic inflammatory status of hemodialysis patients, which favors production of ferritin, but iron and nutritional status may also influence the blood transferrin concentration. These factors make interpretation of transferrin-dependent assessment of body iron stores unreliable and can result in inadequate or overly aggressive iron-replacement therapy.

Oxidative Modification of Low-Density Lipoprotein and Atherogenetic Risk in β-Thalassemia

We investigated the oxidative state of low-density lipoprotein (LDL) in patients with β-thalassemia to determine whether there was an association with atherogenesis. Conjugated diene lipid hydroperoxides (CD) and the level of major lipid antioxidants in LDL, as well as modified LDL protein, were evaluated in 35 β-thalassemia intermedia patients, aged 10 to 60, and compared with age-matched healthy controls. Vitamin E and β-carotene levels in LDL from patients were 45% and 24% of that observed in healthy controls, respectively. In contrast, the mean amount of LDL-CD was threefold higher and lysil residues of apo B-100 were decreased by 17%. LDL-CD in thalassemia patients showed a strong inverse correlation with LDL vitamin E (r = −0.784; P < .0001), while a negative trend was observed with LDL-β–carotene (r = −0.443; P = .149). In the plasma of thalassemia patients, malondialdehyde (MDA), a byproduct of lipid peroxidation, was increased by about twofold, while vitamin E showed a 52% decrease versus healthy controls. LDL-CD were inversely correlated with plasma vitamin E (r = −0.659; P < .0001) and correlated positively with plasma MDA (r = 0.621; P < .0001). Plasma ferritin was positively correlated with LDL-CD (r = 0.583; P =.0002). No correlation was found between the age of the patients and plasma MDA or LDL-CD. The LDL from thalassemia patients was cytotoxic to cultured human fibroblasts and cytotoxicity increased with the content of lipid peroxidation products. Clinical evidence of mild to severe vascular complications in nine of the patients was then matched with levels of LDL-CD, which were 36% to 118% higher than the mean levels of the patients. Our results could account for the incidence of atherogenic vascular diseases often reported in β-thalassemia patients. We suggest that the level of plasma MDA in β-thalassemia patients may represent a sensitive index of the oxidative status of LDL in vivo and of its potential atherogenicity.

Oxidative Modification of Low-Density Lipoprotein and Atherogenetic Risk in β-Thalassemia

We investigated the oxidative state of low-density lipoprotein (LDL) in patients with β-thalassemia to determine whether there was an association with atherogenesis. Conjugated diene lipid hydroperoxides (CD) and the level of major lipid antioxidants in LDL, as well as modified LDL protein, were evaluated in 35 β-thalassemia intermedia patients, aged 10 to 60, and compared with age-matched healthy controls. Vitamin E and β-carotene levels in LDL from patients were 45% and 24% of that observed in healthy controls, respectively. In contrast, the mean amount of LDL-CD was threefold higher and lysil residues of apo B-100 were decreased by 17%. LDL-CD in thalassemia patients showed a strong inverse correlation with LDL vitamin E (r = −0.784; P &lt; .0001), while a negative trend was observed with LDL-β–carotene (r = −0.443; P = .149). In the plasma of thalassemia patients, malondialdehyde (MDA), a byproduct of lipid peroxidation, was increased by about twofold, while vitamin E showed a 52% decrease versus healthy controls. LDL-CD were inversely correlated with plasma vitamin E (r = −0.659; P &lt; .0001) and correlated positively with plasma MDA (r = 0.621; P &lt; .0001). Plasma ferritin was positively correlated with LDL-CD (r = 0.583; P =.0002). No correlation was found between the age of the patients and plasma MDA or LDL-CD. The LDL from thalassemia patients was cytotoxic to cultured human fibroblasts and cytotoxicity increased with the content of lipid peroxidation products. Clinical evidence of mild to severe vascular complications in nine of the patients was then matched with levels of LDL-CD, which were 36% to 118% higher than the mean levels of the patients. Our results could account for the incidence of atherogenic vascular diseases often reported in β-thalassemia patients. We suggest that the level of plasma MDA in β-thalassemia patients may represent a sensitive index of the oxidative status of LDL in vivo and of its potential atherogenicity.