Serum ferritin level is positively associated with insulin resistance and metabolic syndrome in postmenopausal women: A nationwide population-based study
Introduction
Metabolic syndrome (MetS) is characterized by a cluster of several cardiometabolic disorders including abdominal obesity, glucose intolerance, elevated blood pressure, and atherogenic dyslipidemia [1]. The prevalence of MetS in adults has increased globally in recent decades and this upward trend is becoming a significant threat to public health due to its association with increased risk for cardiovascular disease (CVD) and type 2 diabetes mellitus [2], [3].
Although the pathophysiology of MetS is not fully understood, insulin resistance and subclinical low-grade inflammation play a key role in the development and progression of MetS [4], [5]. Moreover, recent epidemiological studies have suggested that menopause is another factor contributing to MetS in women. Postmenopausal women are susceptible to increased weight gain and fat redistribution accompanied by marked changes in estrogen levels [6], [7]. Decreased estrogen levels also influence lipid metabolism in vascular smooth muscle and the endothelium. Thus, menopause is characterized by various detrimental metabolic and vascular changes that lead to insulin resistance and MetS [8], [9], [10], [11].
Ferritin is a major iron storage protein that plays an important role in the homeostasis of intracellular iron. Serum ferritin is secreted by all ferritin-producer cells and it is traditionally regarded as an indicator of iron deficiency or overload. Emerging evidence shows that serum ferritin levels are modestly increased in cardiometabolic diseases such as hypertension, type 2 diabetes and dyslipidemia, which are increasingly being seen as inflammatory diseases. In view of these novel findings, we hypothesized that there would be a positive association between serum ferritin and insulin resistance and metabolic syndrome in postmenopausal women. Thus, we sought to identify associations between serum ferritin levels and insulin resistance and MetS in a representative sample of postmenopausal women in Korea.
Section snippets
Survey overview and study population
This cross-sectional study used data obtained from the 2010–2012 Korean National Health and Nutrition Examination Survey (KNHANES-V), which was conducted by the Korea Centers for Disease Control and Prevention. The KNHANES is a nationwide, representative, population-based survey performed to evaluate the health and nutritional status of Koreans. The survey consists of a health interview survey, a nutrition survey, and a health examination survey. Sampling units were a stratified, multistage,
Results
Table 1 shows the demographic and biochemical characteristics of the participants in relation to serum ferritin quartiles. Mean age was 58.7 ± 0.4 years. In the 4th quartile of ferritin, the mean values of age, BMI, waist circumference, blood pressure, fasting plasma glucose, triglycerides, LDL-cholesterol and HOMA-IR were highest, whereas HDL-cholesterol level was lowest. In addition, the proportion of alcohol drinking, type 2 diabetes and hypertension was highest in the 4th quartile of ferritin.
Discussion
In this nationally representative cross-sectional study, we found that serum ferritin levels were positively and independently associated with insulin resistance and MetS in postmenopausal women after adjusting for potential confounding variables. Our findings are in agreement with the previous findings [12], [13]. In a cross-sectional study of 6044 American adults > 20 years of age who participated in the Third National Health and Nutrition Examination Survey, serum ferritin was associated with
Conclusions
Serum ferritin levels were positively associated with IR and MetS in postmenopausal women. These findings suggest that serum ferritin level in postmenopausal women may help to identify the presence of IR and MetS. Further studies dealing with male sex and a wide range of different age groups would be needed to support the generalizability of our results.
Contributors
M-RC designed the study, wrote and edited the manuscript.
M-RC and J-KP performed the statistical analyses and interpreted the data.
M-RC, W-JC and A-RC contributed to the discussion and revised the manuscript.
Y-JL, as the corresponding author, coordinated the study, interpreted the data, contributed to the discussion, and wrote the manuscript.
All authors read and approved the final version.
Conflict of interest
The authors declare that they have no conflict of interest.
Funding
This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
Ethical approval
The KNHANES was approved by the Institutional Review Board of the Korea Centers for Disease Control and Prevention (approval numbers: 2008-04EXP-01-C, 2009-01CON-03-2C, 2010-02CON-21-C). In addition, this study was conducted in accordance with the ethical principles of the Declaration of Helsinki.
Provenance and peer review
This article has undergone peer review.
Acknowledgements
We thank all those who conducted the 2010–2011 KNHANES as well as the participants in the survey.
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