Previous reports show an association between high serum ferritin levels and metabolic syndrome (MS) in adults. In adolescents, little information is available with obesity and serum ferritin levels.
This is a cross-sectional study. Data were obtained from the 5th Korean National Health and Nutrition Examination Survey (K-NHANES) conducted during 2010 by the Korean Ministry of Health and Welfare. A total of 849 subjects aged 10-18 years participated in the 2010 survey. A body mass index (BMI) ≥95th percentile for age and sex or a BMI ≥25 was used to diagnose as obesity.
The weighted prevalence of obesity was 13.4% (62/462) in male and 8.5% (33/387) in female. We observed significantly higher serum ferritin in male than in female (mean±standard error [SE], 50.5±2.3 µU/L vs. 30.6±1.3 µU/L;
Serum ferritin levels appear to be associated with obesity in Korean male adolescents.
The prevalence of childhood obesity has significantly increased worldwide and has become an important global public health issue
Childhood obesity is associated with complications such as abnormal growth acceleration, glucose intolerance, hypertension, dyslipidemia, nonalcoholic fatty liver disease, polycystic ovary syndrome, pseudotumor cerebri, and psychological problems
Serum ferritin is a widely used clinical biomarker in various epidemiological studies
Therefore, we conducted a cross-sectional study based on data obtained in the 2010 Korean National Health and Nutrition Examination Survey (K-NHANES) to explore the association between elevated serum ferritin level and obesity in Korean male adolescents.
This study was based on data obtained from the fifth K-NHANES conducted in 2010 by the Korean Ministry of Health and Welfare. K-NHANES surveys are conducted annually using a rolling sampling design that involves a complex, stratified, multistage, probability-cluster survey of a representative sample of the noninstitutionalized civilian population in south Korea. All individuals are randomly selected.
A total of 8,958 people participated in the 2010 K-NHANES we limited our study to adolescents aged 10-18 years, and 1,076 subjects were thus included in our analysis. Among these subjects, those with missing data were excluded, resulting in a study population of 849 adolescents (male, 462; female, 387).
Height and weight measurements were performed with the participants wearing light clothing and no shoes. BMI was calculated as weight in kilograms divided by the square of height in meters. A high BMI is a moderately sensitive and very specific indicator of excess adiposity in children
All statistical analyses were carried out using SAS ver. 9.2 (SAS Institute Inc., Cary, NC, USA) were two-sided, and
To make valid inferences accounting for the K-NHANES 2010 complex multistage sampling design, sampling weights were incorporated to produce population estimates. The survey sample weights were calculated taking into consideration the sampling rate, response rate, and proportion of the reference population (2005 Korean National Census Registry), and were used in all analyses to produce estimates representative of children and adolescents aged 10 to 18 years.
All data are presented as mean±standard error (SE) for continuous variables and frequency percentage (SE) for categorical variables. All analyses were performed separately for males and females. Missing data according to each variable were excluded from the P-value computation for the relevant analysis.
The mean values of continuous variables were compared using SAS proc surveymeans procedures. Differences in the proportion of participants who had obesity were analyzed using SAS proc surveyfreq procedures. Serum ferritin was not normally distributed, and geometric means were obtained as representative values.
The clinical characteristics of the study subjects are listed in
A significantly positive association between serum ferritin and age was observed in male (β=5.647,
The weighted prevalence of obesity in male was 13.4% (62/462). No differences were observed between the average ages in the obesity and normal groups. Compared to the normal group, the obesity group showed significantly higher levels for WBC count (6.9±0.2 109/L vs. 6.0±0.1 109/L,
The weighted prevalence of obesity in the female was 8.5% (33/387). The mean age was significantly higher in the obesity group than in the normal group (15.4±0.5 vs. 14.0±0.2,
In male adolescent, after adjusting for age, associations were observed between serum ferritin and abdominal obesity (β=12.98,
Serum ferritin is a major iron storage protein in all cell types such as in the liver and spleen (L-isoferritin), and in the heart and kidneys (H-isoferritin), and its distribution patterns are different according to age, sex, and race
Previous studies have investigated the relationship between obesity, central obesity and serum ferritin. Lecube et al.
In this study, we analyzed 2010 K-NHANES data for 849 Korean children and adolescents (aged 10-18 years) to examine the associations between serum ferritin and both obesity and components of MS. The results show that the prevalence of obesity is 13.4% (62/462) in male and 8.5% (33/387) in female. Serum ferritin appears to be significantly different between the sexes. In male, mean serum ferritin level was markedly higher than in female, and serum ferritin increased significantly with increasing age. Unlike in male, we did not observe a trend toward increasing serum ferritin with age in female, which is consistent with the results of previous studies conducted in Japanese children
According to International Diabetes Federation (IDF) criteria, adolescents with abdominal obesity (WC≥90th percentile for age and sex) and 2 or more of the following criteria: TG, ≥150 mg/dL; HDL, ≤40 mg/dL; fasting glucose, ≥100 mg/dL; and systolic BP, ≥130 mmHg; or diastolic BP, ≥85 mmHg were diagnosed with MetS. In our results, the prevalence of MS based on the IDF consensus
In male, serum ferritin, WBC count, FBS, TC, TG, LDL, insulin, HOMA-IR, and systolic and diastolic BP were significantly higher and HDL was significantly lower in the obesity group than in the normal group. In female, WBC, TG, insulin, and HOMA-IR levels were significantly higher and HDL levels were significantly lower in the obesity group than in the normal group. After adjusting for age, serum ferritin was positively associated with both abdominal obesity (β=12.98,
BMI is an excellent indicator for accurately measuring body fat and is a very specific and reliable indicator of childhood obesity, and WC is frequently used as an indicator of abdominal obesity
Recent studies have shown an association between obesity and low-grade chronic inflammation resulting from chronic activation of the innate immune system, which is characterized by abnormal cytokine production, increased acute-phase reactants, and activation of inflammatory signaling pathways
In the past, adipose tissue was thought of as just a reservoir of energy stored as TG. However, many recent studies have reported additional functions of adipocytes, such as their being dynamic endocrine cells that secrete free fatty acids and inflammatory cytokines (tumor necrosis factor [TNF]-alpha and interleukin [IL]-6, adiponectin, plasminogen activator inhibitor-1, leptin and resistin)
Iron is a transitional metal capable of causing oxidative stress-induced tissue damage by catalyzing the conversion of hydrogen peroxide to free radicals that attack cellular membranes, proteins, and DNA
The relationships with insulin resistance and inflammation are similar for serum ferritin and obesity. Furthermore, the activation of inflammatory cytokines in obesity increases the transcription of ferritin messenger RNA, which transfers ferritin to hepatocytes
To our knowledge, no studies have shown associations among obesity, serum ferritin, and metabolic disorders in healthy Korean children and adolescents or on an association between increases in serum ferritin and aging. Hence, the results of our study could aid in developing measures for managing and improving the health of obese adolescents.
In conclusion, we observed associations between serum ferritin and abdominal obesity and obesity in Korean male adolescents. We suggest that serum ferritin could be used as an indicator for obesity or metabolic disorders in children. Further research, including longitudinal studies, is necessary to confirm these relationships.
No potential conflict of interest relevant to this article was reported.
Significant positive association between serum ferritin level and age in the males (A: β=5.647,
Multiple parameters by sex for children and adolescents aged 10 to 18 years; the Korean National Health and Nutrition Survey
Characteristic | Male (n=462) | Female (n=387) | |
---|---|---|---|
Age (yr) | 14.2±0.1 | 14.1±0.2 | 0.7770 |
Hb (g/dL) | 14.6±0.1 | 13.3±0.1 | <0.0001 |
Hct (%) | 42.9±0.2 | 39.6±0.2 | <0.0001 |
WBC (109/L) | 6.2±0.1 | 6.1±0.1 | 0.6990 |
FBS (mg/L) | 89.1±0.4 | 88.5±0.4 | 0.2250 |
TC (mg/dL) | 152.40±1.74 | 163.3±1.5 | <0.0001 |
TG (mg/dL) | 83.9±3.3 | 85.7±3.37 | 0.6770 |
HDL (mg/dL) | 48.0±0.5 | 50.6±0.6 | <0.0010 |
LDL (mg/dL) | 91.6±2.1 | 97.70±1.87 | 0.0510 |
Insulin (μU/mL) | 13.3±0.4 | 13.7±0.4 | 0.4000 |
HOMA-IR | 3.0±0.1 | 3.07±0.10 | 0.5420 |
Systolic BP (mmHg) | 106.3±0.7 | 101.9±0.7 | <0.0001 |
Diastolic BP (mmHg) | 64.4±0.6 | 63.7±0.6 | 0.3320 |
Ferritin (μU/L) | 50.5±2.3 | 30.6±1.3 | <0.0001 |
Iron (μU/dL) | 114.70±2.67 | 99.9±2.4 | <0.0001 |
Values are presented as mean±standard error.
Hb, hemoglobin; Hct, hematocrit; WBC, white blood cell; FBS, fasting blood sugar; TC, total cholesterol; TG, triglycerides; HDL, high-density lipoprotein; LDL, low-density lipoprotein; HOMA-IR, homeostasis model assessment for insulin resistance; BP, blood pressure.
Missing data were excluded for
b)Weighted proportion.
Characteristics and laboratory data for subjects in the obesity and normal group of Korean adolescents
Characteristic | Male (n=462) |
Female (n=387) |
||||
---|---|---|---|---|---|---|
Normal | Obesity | Normal | Obesity | |||
Subjects | 400 (86.6) | 62 (13.4) | - | 354 (91.5) | 33 (8.5) | - |
Age (yr) | 14.2±0.1 | 14.5±0.5 | 0.5090 | 14.0±0.2 | 15.4±0.5 | 0.005 |
Hb (g/dL) | 14.6±0.1 | 14.8±0.2 | 0.1790 | 13.3±0.1 | 13.3±0.1 | 0.655 |
Hct (%) | 42.8±0.2 | 43.7±0.5 | 0.0590 | 39.6±0.2 | 39.7±0.4 | 0.910 |
WBC (109/L) | 6.0±0.1 | 6.9±0.2 | <0.0001 | 6.0±0.1 | 6.8±0.2 | 0.001 |
FBS (mg/L) | 88.8±0.4 | 91.1±1.1 | 0.0400 | 88.3±0.4 | 89.9±1.8 | 0.401 |
TC (mg/dL) | 149.5±1.6 | 170.7±5.2 | 0.0001 | 163.5±1.5 | 161.7±5.1 | 0.740 |
TG (mg/dL) | 77.2±2.7 | 126.8±9.4 | <0.0001 | 83.3±3.5 | 107.0±11.4 | 0.043 |
HDL (mg/dL) | 48.6±0.5 | 44.0±1.5 | 0.0020 | 51.4±0.6 | 43.5±1.8 | <0.001 |
LDL (mg/dL) | 86.1±2.0 | 119.8±6.4 | 0.0001 | 97.6±1.8 | 99.4±7.0 | 0.791 |
Insulin (μU/mL) | 12.1±0.3 | 20.9±1.4 | <0.0001 | 13.3±0.4 | 17.0±1.7 | 0.021 |
HOMA-IR | 2.7±0.1 | 4.7±0.3 | <0.0001 | 2.9±0.1 | 3.8±0.4 | 0.014 |
Systolic BP (mmHg) | 104.8±0.8 | 116.1±1.8 | <0.0001 | 101.7±0.7 | 103.1±1.5 | 0.344 |
Diastolic BP (mmHg) | 63.7±0.7 | 69.0±1.6 | 0.0030 | 63.61±0.6 | 64.4±1.2 | 0.529 |
Ferritin (μU/L) | 47.7±2.0 | 68.9±9.4 | 0.0270 | 29.6±1.3 | 39.8±6.6 | 0.133 |
Iron (μU/dL) | 114.6±2.8 | 115.0±6.2 | 0.9520 | 99.0±2.6 | 07.6±6.2 | 0.204 |
Values are presented as number (%) or mean±standard error.
Hb, hemoglobin; Hct, hematocrit; WBC, white blood cell; FBS, fasting blood sugar; TC, total cholesterol; TG, triglyceride; HDL, high-density lipoprotein; LDL, low-density lipoprotein; HOMA-IR, homeostasis model assessment for insulin resistance; BP, blood pressure.
Missing data were excluded for
b)Weighted proportion
The association between serum ferritin level and metabolic syndrome components in male Korean adolescents
Metabolic syndrome component | Ferritin |
|||
---|---|---|---|---|
β | Standard error | Crude ( |
Adjusted ( |
|
FBS≥100 (mg/L) | –1.598 | 12.290 | 0.897 | 0.436 |
TG≥150 (mg/dL) | 7.065 | 9.292 | 0.448 | 0.589 |
HDL≤40 (mg/dL) | 8.025 | 7.104 | 0.261 | 0.167 |
SBP≥130 or DBP≥85 (mmHg) | 24.244 | 17.461 | 0.167 | 0.471 |
WC≥90th | 12.980 | 9.969 | 0.195 | 0.021 |
BMI≥95th or BMI≥25 (kg/m2) | 21.196 | 9.453 | 0.027 | 0.016 |
Tested by linear analysis and adjusted by age.
FBS, fasting blood sugar; TG, triglyceride; HDL, high-density lipoprotein; SBP, systolic blood pressure; DBP, diastolic blood pressure; WC, waist circumference; BMI, body mass index,