Serum ferritin concentrations predict incidence of metabolic syndrome in rural Korean adults

Abstract

Keywords: ferritin; infl ammation; insulin resistance; metabolic syndrome; oxidative stress.Serum ferritin concentrations refl ect iron storage in the body and are associated with systemic infl ammation and insulin function. Body iron, a transitional ion, can play a role in the conversion of less-reactive free radicals to more-reactive hydroxyl radicals, which acts as oxidative stressors at multiple cellular targets (1) . Concentrations of serum ferritin, an acute phase protein, are elevated in infl ammatory environments, which contribute to cardiometabolic diseases (2) . Elevated serum ferritin and iron concentrations are related to insulin resistance and hyperinsulinemia in the early phases, while chronic exposure to these elevated concentrations subsequently results in insuffi cient insulin production in the more advanced phases (3,4) . Due to the lack of prospective evidence on the independent relationship between serum ferritin concentrations and the incidence of metabolic syndrome (MetS), we conducted this study to determine whether elevated serum ferritin concentrations could predict MetS development.The Korean Genomic Rural Cohort (KGRC) is an ongoing multicenter cohort study with 10,114 adult participants aged 40 years and older. Participants who have been diagnosed with any malignancy or have incomplete laboratory data were excluded in this study. Participants who were taking antihypertensive, anti-diabetic, or anti-dyslipidemic medication, or dietary supplements including iron, were also excluded. Finally, 865 eligible subjects without MetS at baseline were selected. All participants gave written informed consent and this study was approved by the Institutional Review Board of Wonju Christian Hospital.Trained medical staff performed physical examinations following standard procedures. A blood sample was obtained after overnight fasting. The samples were stored at -80 ° C and were analyzed within 1 week. More detailed methods of quality and accuracy control were described in our previous article (5) .We defi ned MetS using a harmonizing defi nition published in 2009, defi ned as the presence of three or more of the following criteria (6) : waist circumference, ≥ 90 cm in men and ≥ 80 cm in women; systolic blood pressure ≥ 130 mm Hg, diastolic blood pressure ≥ 85 mm Hg, or on anti-hypertensive medication for hypertension; fasting plasma glucose concentrations ≥ 5.5 mmol/L or on anti-diabetic medication for hyperglycemia; triglyceride concentrations ≥ 1.7 mmol/L or on triglyceridelowering medication for hypertriglyceridemia; high-density lipoprotein cholesterol (HDL-C) concentrations, < 1.0 mmol/L in men and < 1.3 mmol/L in women, or on drug treatment for reduced HDL-C concentrations. A cut-off point for waist circumference has been adopted specifi cally for Asian populations. Insulin resistance was calculated using the homeostasis model assessment of insulin resistance (HOMA-IR).Serum ferritin concentrations were categorized into tertile groups for men, and pre-or post-menopausal women. Analysis of varia...

Soluble transferrin receptor levels are positively associated with insulin resistance but not with the metabolic syndrome or its individual components

“…Theoretically, in men and postmenopausal women the relationship between ferritin and cardiometabolic risk might be more obvious due to higher iron accumulation than in women who lose iron during menstruation. This is in line with studies describing no association between ferritin and MetS in premenopausal women (33, 34). However, several studies have also reported significant relationship between ferritin and MetS in premenopausal women (35,36,37,38).…”

Serum ferritin levels are associated with insulin resistance in Chinese men and post-menopausal women: the Shanghai Changfeng study

“…These may explain the discrepancy found in the link between ferritin levels and IR in the women. Moreover, statistical power could also explain the discrepant findings, because most of the studies describing associations had larger sample sizes for pre-menopausal women than those with no association (21)(22)(23) .…”

Ferritin levels throughout childhood and metabolic syndrome in adolescent stage

“…This sex difference appears to be explained by a threshold effect derived from higher levels of cardiometabolic risk factors in boys at the adolescent stage, rather than by higher iron stores in boys since at 5 years there was no significant sex difference in ferritin levels. Two recent prospective studies in adults which evaluated both sexes have also shown significant associations between ferritin and development of MetS with stronger associations for men than for premenopausal women, 16,17 although one study in a Swiss population did not find difference by sex. 18 However, some cross-sectional studies have described non-significant ferritin-MetS associations in men.…”