Clinical significance of serum ferritin level as an independent predictor of insulin resistance in Korean men

Influence of serum ferritin combined with blood cadmium concentrations on blood pressure and hypertension: From the Korean National Health and Nutrition Examination Survey

BACKGROUND

Previous studies have suggested that cadmium (Cd) exposure and serum ferritin levels may influence the development of hypertension.

OBJECTIVE

We evaluated whether the association between blood Cd levels and the development of hypertension could be modified by serum ferritin levels in a representative sample of the adult population of South Korea.

METHODS

We used data from the Korean National Health and Nutrition Examination Survey (2008-2012), a nationally representative, cross-sectional, population-based study. We included 5752 adults aged 19 years and older who had records of blood Cd and ferritin levels and blood pressure measurements. Multiple logistic regression was used to examine the association between Cd exposure and the development of hypertension, as well as the modifying effects of serum ferritin.

RESULTS

Men had higher levels of serum ferritin, and women had higher levels of Cd. Smoking in men was significantly associated with high blood pressure and risk of hypertension. Significantly fewer women were smokers, and the combination of abnormal serum ferritin levels and high Cd levels was significantly associated with high systolic blood pressure [odds ratio (OR) = 2.11; 95% confidence interval (CI) = 1.04-4.28], high diastolic blood pressure (OR = 2.07; 95% CI = 1.04-4.12), and increased hypertension risk (OR = 1.83; 95% CI = 1.03-3.25) in women who never smoked.

CONCLUSIONS

Our results provide further evidence that individuals with abnormal serum ferritin levels should limit their exposure to Cd to prevent hypertension.

Association of serum ferritin with metabolic syndrome in eight cities in China

Objective

This study aims to evaluate the cross‐sectional association of serum ferritin (SF) and the risk of metabolic syndrome (MetS) and its components among adults in eight cities in China.

Methods

Subjects were recruited using a combination of systematic cluster random sampling and purposive sampling in eight cities in China. The sociodemographic characteristics, data of lifestyle factors, self‐reported disease history, and 24‐hr dietary intake were obtained using a validated questionnaire. Anthropometry was performed, and fasting blood was collected to test the SF, fasting blood glucose (FBG), insulin, high‐sensitivity C‐reactive protein (hs‐CRP), triglycerides (TG), and cholesterols. Logistic and linear regression analyses were conducted to investigate the associations, adjusting for age, city level, smoking, drinking, weekly moderate‐to‐vigorous activity, dietary factors, hs‐CRP, and BMI.

Results

Serum ferritin level is positively correlated with total cholesterol, TG, FBG, HOMA‐IR, and hs‐CRP after adjusting for age and BMI. The odds ratio (OR) for MetS in the highest quartile of SF was 2.23 (1.32, 3.77) after adjusting for men, compared with the lowest quartile. An elevated ferritin concentration was significantly related to hypertriglyceridemia (p < .001) and elevated glucose (p = .013) among men, but not among women. Furthermore, compared with Q1, the OR for insulin resistance in the ferritin Q4 group was 3.08 (1.50, 6.32) among men and 1.96 (1.19, 3.24) among women.

Conclusion

A positive association between elevated SF and MetS and its components including hypertriglyceridemia and elevated glucose was found in multivariate analyses among men, and SF levels are independently associated with IR.

Independent and combined effects of dietary iron composition and selected risk factors on the risk of NAFLD in a Chinese population

Iron is an essential mineral required for most forms of life. However, very little is known in relation to the different forms of dietary iron on the development of NAFLD. The aims of this study were to investigate the effects of iron intake from different food types on risk of NAFLD and whether this effect may be modified by other factors. We conducted a hospital-based case–control study including 1,273 NAFLD cases and 1,273 gender and age-matched controls. We conducted in-person interviews while participants completed a questionnaire on food habits. We assessed animal- and plant-derived intake of iron and fat. We observed that animal-derived iron intake (>4.16 mg/day) was positively associated with augmented NAFLD risk in a Chinese population (OR_adjusted = 1.66 in the highest quartile compared with the lowest, 95% confidence interval [CI] = 1.01–2.73). In contrast, a high consumption of iron (>16.87 mg/day) from plant-based foods was associated with a decreased NAFLD risk (ORadjusted = 0.61 in the highest quartile compared with the lowest; 95% CI = 0.40–0.935). In addition, high intake of fat or being overweight may exacerbate this effect. Reduced consumption of iron and fat from animal sources could reduce NAFLD risk, as would weight loss.

Association between serum ferritin and hypertension according to the working type in Korean men: the fifth Korean National Health and nutrition examination survey 2010-2012

Background

Several studies suggest that serum ferritin concentrations reflect systemic inflammation, and high ferritin levels can increase the risk of hypertension in adult men. Shift work is also known to increase the risk of hypertension; however, there has been no study about the relationship between serum ferritin levels and the prevalence of hypertension according to the working type.

Methods

This cross-sectional study included 4,442 male participants (3,651 daytime workers and 791 shift workers) who participated in the fifth Korean National Health and Nutrition Examination Survey. Hypertension was defined as a systolic blood pressure greater than or equal to 140 mmHg, a diastolic blood pressure greater than or equal to 90 mmHg or the current use of antihypertensive medications regardless of blood pressure values. For the statistical analyses, serum ferritin levels were reclassified into quartiles, and complex sample analyses were used to evaluate the relationship between serum ferritin levels and the prevalence of hypertension according to the working type in this study.

Results

Serum ferritin and shift work were positively associated with the prevalence of hypertension. The effect of interaction was above multiplicative. When compared to participants in the lowest serum ferritin quartile, the odds ratio for hypertension for participants in the highest serum ferritin quartile was 1.372 (1.027–1.833) in daytime workers and 2.009 (1.042–3.873) in shift workers after adjustment.

Conclusions

The prevalence of hypertension increased as ferritin levels increased in individuals, especially in shift workers.

High serum ferritin levels are associated with insulin resistance but not with impaired glucose tolerance in a healthy people population

AIM

To assess the association between elevated serum ferritin levels and the presence of insulin resistance (IR) or impaired glucose tolerance (IGT) in a population of individuals with no endocrine or metabolic disorders background.

METHODS

Analytical cross-sectional study, carried out in adults of both sexes with no medical history of type 2 diabetes mellitus (T2DM) or other metabolic or endocrine disorder, who attended the outpatient service of a private clinic in Lima-Peru during 2012-2014 period. Impaired serum ferritin levels were defined as serum ferritin values >300μg/L in men and >200μg/L in women. IR was defined as a Homeostasis Model Assessment (HOMA-IR) value ≥3.8 and IGT was defined as an oral glucose tolerance test (OGTT) value between 126mg/dL and 199mg/dL. The reported association measure was the prevalence ratio (PR) with their respective 95% confidence intervals (95% CI).

RESULTS

We analyzed 213 participants, the average age was 35.8±11.1years and 35.7% were males. The prevalence of impaired serum ferritin levels, IR and IGT in the population was 12.7%, 33.3% and 9.9% respectively. In the adjusted Poisson regression models, the prevalence of IR was higher among the group with impaired serum ferritin levels (PR=1.74; 95%CI:1.18-2.56); however, we found no association between impaired serum ferritin levels and IGT (PR=1.42; 95%CI:0.47-4.30).

CONCLUSIONS

Impaired levels of serum ferritin are associated with IR, nevertheless, not with IGT in a metabolically healthy population. Serum ferritin could be considered as an early marker of IR prior to the onset of glycaemia disorders.

The Risk for Insulin Resistance according to the Degree of Non-Alcoholic Fatty Liver Disease in Korean Men

Insulin resistance (IR) plays a significant role in the development and progression of non-alcoholic fatty liver disease (NAFLD). However, the natural course of insulin sensitivity under NAFLD remained unclear. Accordingly, this study was designed to investigate the effect of NAFLD on insulin resistance. A total of 20,628 Korean men without homeostasis model assessment of insulin resistance (HOMA-IR < 2.7) were followed-up for 5 years. They were serially checked for HOMA-IR to monitor the development of IR (HOMA-IR ≥ 2.7). The incidence rate of IR increased according to the degree of NAFLD (normal: 11.6%, mild: 28.8%, moderate to severe: 40.5%, P < 0.001). Cox proportional hazards model showed that HRs (95% CI) for IR increased proportionally to the degree of NAFLD (mild: 1.19 [1.02-1.39], moderate to severe: 1.32 [1.08-1.57]). IR was more potentially associated with the more progressive NAFLD than normal and milder state. In addition, NAFLD was the independent risk factor of the development of IR. These results suggest the potential availability of NAFLD as a predictor of IR.

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.