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 is a ubiquitous metal of vital importance to the normal physiologic processes of many organisms (1). The serum ferritin concentration reflects iron stores in the body (2).There have been several studies that showed the significant association between elevated serum ferritin levels and metabolic disorders. In a population study of Finnish men, serum ferritin levels were correlated with fasting serum glucose and insulin concentrations (3). In several other studies, elevated serum ferritin concentrations were reported to be associated with cardiovascular disease (4–6), essential hypertension (7), insulin resistance (8,9), diabetes (10,11), gestational diabetes mellitus (12), and central adiposity (13). In addition, recent studies showed that serum ferritin levels are positively associated with the prevalence of metabolic syndrome (MetS) in western countries (14,15). In the Asian population, some studies reported the relationship between serum ferritin concentrations and the prevalence of MetS (16,17). However, most of the studies have been confined to the cross-sectional nature. To the best of our knowledge, no prospective research has been conducted to evaluate the longitudinal association between baseline serum ferritin levels and the development of MetS. Therefore, we performed this study to assess the longitudinal effects of baseline serum ferritin levels on the development of MetS during a 5-year follow-up period in middle-aged Korean men.