Serum ferritin levels are positively associated with bone mineral density in elderly Korean men: the 2008-2010 Korea National Health and Nutrition Examination Surveys.

A possible negative effect of iron overload on bone metabolism has been suggested by the fact that patients with hemochromatosis, thalassemia, and sickle cell anemia have lower bone mineral density than the general population. However, the influence of iron overload on bone health in the general population is uncertain. The aim of this study was to investigate the relationship between serum ferritin levels and bone mineral density (BMD) in elderly Koreans. A total of 2,943 subjects aged 65 years and over who participated in the 2008-2010 Korea National Health and Nutrition Examination Surveys were included in this study. Age, physical activity, current smoking status, alcohol consumption, education level, household income, and dietary assessment were surveyed by a face-to-face interview. BMD was measured at the lumbar spine and femur by dual-energy X-ray absorptiometry, and other biochemical markers, including serum ferritin, 25-hydroxyvitamin D3, serum alkaline phosphatase, and parathyroid hormone, were assayed. After adjusting for age and body mass index, we found an association between BMD of the total lumbar spine, total femur, and femur neck and levels of alkaline phosphatase, parathyroid hormone, vitamin D3, and daily intake of calcium and protein. Serum ferritin levels were positively associated with BMD of the total lumbar spine, total femur, and femur neck after adjusting for all covariates in men, but not in women. This study suggests a positive association between serum ferritin levels and BMD in elderly South Korean men without hematologic disorders. Further study is warranted to verify the effects of iron on bone metabolism.

New reference data on bone mineral density and the prevalence of osteoporosis in Korean adults aged 50 years or older: the Korea National Health and Nutrition Examination Survey 2008-2010.

This cross-sectional study was performed to investigate the reference values for bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) and the prevalence of osteoporosis in the Korean population by applying domestic reference data. In total, 25,043 Korean adults ≥20 yr of age (11,792 men and 13,251 women) participated in the study. The BMDs of the total hip, femoral neck, and lumbar spine were measured by DXA (Discovery-W, Hologic Inc.), and subjects with a BMD - 2.5 standard deviations or lower than the mean BMD for young adults (20-29 yr old) were considered to have osteoporosis. When applying the new reference values determined in this study from Korean subjects, the overall prevalence of osteoporosis increased in men aged ≥50 yr compared with that provided by the DXA manufacturer from Japanese subjects (12.2% vs. 7.8%, P<0.001) and decreased in postmenopausal women aged ≥50 yr (32.9% vs. 38.7%, P<0.001). According to the findings of this study, use of the reference values provided by the DXA manufacturer has resulted in the underdiagnosis of osteoporosis in Korean men and the overdiagnosis of osteoporosis in Korean women. Our data will serve as valuable reference standards for the diagnosis and management for osteoporosis in the Korean population.

Dose-related association between urinary cotinine-verified smoking status and dyslipidemia among Korean men: the 2008-2010 Korea National Health and Nutrition Examination Survey.

This cross-sectionally designed study was based on data collected during the 2008-2010 Korea National Health and Nutrition Examination Survey. A total 3231 South Korean men aged more than 19 years were included. Urinary cotinine concentrations were measured. Smoking status was defined using questionnaire responses and urinary cotinine concentrations. Hierarchical multivariate logistic regression analyses were used to assess the association of urinary cotinine concentrations with the prevalence of dyslipidemia and various parameters of dyslipidemia. There is a significant dose-related association between smoking as assessed by urinary cotinine concentration and dyslipidemia and various parameters of dyslipidemia among South Korean men.

Socioeconomic status and dyslipidemia in Korean adults: the 2008-2010 Korea National Health and Nutrition Examination Survey.

OBJECTIVE: This study investigated the relationship between socioeconomic status (SES) and dyslipidemia and various parameters of dyslipidemia among Korean adults. METHODS: Data from the 2008-2010 Korea National Health and Nutrition Examination Survey were used in this study. A total of 19,041 Korean adults greater than 19years old participated in the study. The SES was assessed by monthly household income and education level. The relationship of SES to the risk of dyslipidemia was assessed with multivariate logistic regression analysis after adjusting for potential confounders. RESULTS: The prevalence of dyslipidemia was 37.4% among Korean adults. In men, household income level was positively associated with prevalence and risks of several parameters of dyslipidemia, and education level had positive associations with the risks of dyslipidemia and parameters of dyslipidemia. However, low SES was linked to increased prevalence and risks of dyslipidemia (P for trend<0.05) and parameters of dyslipidemia in women. CONCLUSIONS: Socioeconomic disparities in dyslipidemia were found in the Korean population. Also, there were gender differences in the relationship between SES and dyslipidemia. These disparities should be considered when performing risk calculations and screening for dyslipidemia, which will ultimately help prevent cardiovascular disease.

Prevalence and related risk factors of albuminuria in Korean adults: the 2011 Korea National Health and Nutrition Examination Survey.

BACKGROUND/AIMS: Albuminuria is known to be associated with an increased risk for cardiovascular morbidity and mortality even in the general population. We aimed at investigating the prevalence and related risk factors of albuminuria among Korean adults. METHODS: This study was based on data collected during the 2011 Korea National Health and Nutrition Examination Survey. A total of 5,365 Korean adults were included in the general population group, and 3,282 of these participants were included in the nondiabetic, nonhypertensive population group. Albuminuria was defined by a urine albumin-to-creatinine ratio value within the range of 3.4-34 mg/mmol (30-300 µg/mg). RESULTS: The overall prevalence of albuminuria was 5.2% of the general population and 2.1% of the nondiabetic, nonhypertensive population. Factors associated with the risk of albuminuria in the general population were age, systolic blood pressure (SBP), glycated hemoglobin (HbA1c) level in men, and SBP and HbA1c level in women. In the nondiabetic, nonhypertensive population, age and fasting plasma glucose levels were significantly associated with an increased risk for albuminuria in men, and with central obesity, triglyceride level and smoking status in women. CONCLUSION: Albuminuria is prevalent in the nondiabetic, nonhypertensive population as well as general population of Korea. The increased risk of albuminuria was independently associated with several cardiovascular risk factors in the general population, and also in the nondiabetic, nonhypertensive population.

Low bone mineral density is associated with dyslipidemia in South Korean men: the 2008-2010 Korean National Health and Nutrition Examination Survey.

This study examined the relationship between bone mineral density (BMD) and dyslipidemia in South Korean men. Data from 6,300 men who participated in the Korean National Health and Nutrition Examination Survey from 2008 to 2010 were analyzed, including serum levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglyceride (TG) after 8 hours of fasting and mean BMD measured at the lumbar spine (LS), total hip (TH), and femoral neck (FN). Dyslipidemia was defined according to the criteria of the National Cholesterol Education Program Adult Treatment Panel III. Other parameters of dyslipidemia were also calculated, such as TG/HDL-C, TC/HDL-C, non-HDL-C (NHDL-C), and LDL-C/HDL-C. Men with dyslipidemia and high levels of TG, TG/HDL-C, TC/HDL-C, NHDL-C, and LDL-C/HDL-C had lower BMD than men without dyslipidemia at the LS, TH, and FN after adjustment for age and body mass index (all p<0.01). On multivariable regression analysis, all odds ratios for high levels of TG, TG/HDL-C, TC/HDL-C, NHDL-C, and LDL-C/HDL-C with an increase in BMD (per standard deviation) were <1 at all 3 sites after adjustment for age and body mass index (model 1). After adjustment for all covariates, only odds ratios for high levels of TG, TG/HDL-C, TC/HDL-C, and NHDL-C were <1 at all 3 sites (model 2), but an increase in BMD was not associated with high LDL-C levels in models 1 and 2. In conclusion, BMD was inversely correlated with parameters of atherogenic dyslipidemia in South Korean men.

An increase in serum uric acid concentrations is associated with an increase in the Framingham risk score in Korean adults.

BACKGROUND: Uric acid is a novel cardiovascular disease (CVD) factor, but its use as an independent risk factor for CVD remains controversial. Here, we examined the correlation between Framingham risk score (FRS) and serum uric acid concentrations in asymptomatic Korean adults. METHODS: This cross-sectional study was performed on 8035 Korean adults. Besides FRS, we measured body mass index, fasting blood glucose, homeostasis model assessment of insulin resistance, creatinine, γ-glutamyltransferase, the lipid profile, uric acid, high-sensitive C-reactive protein, and the white blood cell count. All subjects were placed into one of three risk groups according to their FRS. RESULTS: All CVD related factors were significantly different in the three FRS groups. The increments of uric acid increased significantly FRS from the 10-year risk 0%-9% group to the >10% group after adjusting for other CVD-related factors using ordinal logistic regression analysis. Analyses of the three age groups showed similar effects. CONCLUSIONS: An increased uric acid concentration is associated with an increase in coronary heart disease risk calculated from the FRS, and doctors need to pay attention to this CVD risk in apparently healthy adults with hyperuricemia.

Sensitive DNA biosensor based on a long-period grating formed on the side-polished fiber surface.

We demonstrate a sensitive DNA biosensor based on a long period grating (LPG) formed by a photolithograph process on the surface of a side-polished fiber. The biomolecules of the biosensor were immobilized on the silica surface between LPG patterns. The resonance wavelength was red-shifted after the binding of the poly-L-lysine, probe ssDNA and target ssDNA to the sensor surface. The overall wavelength shift after the successful DNA hybridization was 1.82 nm. The proposed LPG-based DNA biosensor is approximately 2.5 times more sensitive than the previously reported fiber grating-based DNA biosensors.

Meshed index profile method for photonic crystal fibers with arbitrary structures.

A meshed index profile method, which is based on the localized function method, is demonstrated for analyzing modal characteristics of photonic crystal fibers with arbitrary air-hole structures. The index profile of PCF, which is expressed as a sum of meshed unit matrix, is substituted to full wave equation. By solving this full wave equation, we obtain the modal characteristics of the PCF such as the mode field distribution, the birefringence and the waveguide dispersion. The accuracy of the proposed meshed index profile method (MIPM) is demonstrated by examining the effective index and the birefringence of the two degenerate fundamental modes in the PCF with a triangular air-hole lattice. The MIPM is not restricted to the PCF structure and will be useful in designing various PCF devices.

Prognostic factors affecting the clinical outcome of adenoid cystic carcinoma of the head and neck.

BACKGROUND: Adenoid cystic carcinoma (ACC) is an uncommon tumor, constituting approximately 10% of all head and neck tumors. Classically, ACC has been described as a tumor with indolent, but persistent and recurrent, growth and late onset of metastases, leading eventually to death. This study assessed the prognostic factors affecting the clinical outcome in patients with ACC in the head and neck region. METHODS: We performed a retrospective study of 42 patients who underwent primary tumor resection or radiotherapy with curative intent and evaluated the clinical parameters, treatment and clinical outcomes. RESULTS: Forty-two patients (18 males and 24 females with a median age of 65 years) received curative treatment. The overall 3- and 5-year survival was 87.4% and 55.3%, respectively, whereas the 3- and 5-year disease-free survival was 64.3% and 36.1%, respectively. Of the 32 patients in whom recurrence could be evaluated, 18 (56.3%) developed distant metastases, with the lung (72.2%) being the most common site. Perivascular invasion influenced metastasis to the lung with borderline significance (P = 0.053). The recurrence rate was higher (P = 0.045) in patients with high-grade tumor. The status of lymph node metastasis was significantly associated with overall survival (P = 0.030). CONCLUSIONS: High tumor grade and lymph node involvement were predictive of recurrence and overall survival, respectively. Despite aggressive treatment, it seems to be impossible to prevent the development of distant metastasis. Therefore, more research is needed to identify molecular biomarkers that predict the clinical outcome and to develop effective treatment for patients with ACC.

Ultra-flattened-dispersion selectively liquid-filled photonic crystal fibers.

We propose a method to control the chromatic dispersion properties of photonic crystal fibers using the selective hole filling technique. The method is based on a single hole-size fiber geometry, and uses an appropriate index-matching liquid to modify the effective size of the filled holes. The dependence of dispersion properties of the fiber on the design parameters such as the refractive index of the liquid, lattice constant and hole diameter are studied numerically. It is shown that very small dispersion values between 0+/-0.5ps/nm-km can be achieved over a bandwidth of 430-510nm in the communication wavelength region of 1300-1900nm. Three such designs are proposed with air hole diameters in the range 1.5-2.0microm.

Clinical pharmacokinetics of oxaliplatin and 5-fluorouracil administered in combination with leucovorin in Korean patients with advanced colorectal cancer.

PURPOSE: Oxaliplatin and 5-fluorouracil (5-FU) act synergistically in colorectal cancer. Here, we evaluated the pharmacokinetics of oxaliplatin and 5-FU administered in combination with leucovorin in Korean advanced colorectal cancer patients. METHODS: Nine patients with advanced colorectal cancer were included in this study. The 3-week regimen consisted of oxaliplatin (2-h infusion, 130 mg/m(2)on day 1) followed by 5-FU and leucovorin (2-h infusion, 425 and 20 mg/m(2), respectively, from day 1 to day 5). Blood samples were taken and platinum concentrations in total plasma, plasma ultrafiltrate, and RBCs were determined. Plasma concentrations of 5-FU were also determined. RESULTS: The C (max) of oxaliplatin was observed at the end of infusion, with mean values of 4.66, 0.84, and 2.69 microg/ml for total plasma, plasma ultrafiltrate, and RBC samples, respectively. C (max) ratios of total/free were significantly higher than those reported in other ethnic groups. An accumulation of platinum was observed in RBCs, but not in total plasma and plasma ultrafiltrate samples. A significant correlation was found between the total body clearance of ultrafiltrable platinum and creatinine clearance. The C (max) of plasma 5-FU ranged from 23.9 to 533.8 ng/ml, indicating large inter-patient pharmacokinetic variations. CONCLUSIONS: This study shows that pharmacokinetics of oxaliplatin in Korean patients is comparable with that of other ethic groups, except for the higher C (max) ratios of total/free. The C (max) of 5-FU in plasma showed large variations among patients. Antitumor efficacy in Korean advanced colorectal cancer patients given oxaliplatin and 5-FU should be further evaluated with respect to pharmacokinetic variabilities.

The Association between Taking Dietary Supplements and Healthy Habits among Korean Adults: Results from the Fifth Korea National Health and Nutritional Examination Survey (2010-2012).

BACKGROUND: Recently, the number of people interested in health in South Korea has increased, and the rate of dietary supplement use is rising. Researchers have hypothesized that the rate of practicing healthy habits is higher among those who use dietary supplements than those who do not. Therefore, this study aimed to discover the association between taking dietary supplements and practicing various healthy habits in the Korean, adult population. METHODS: The sample included 15,789 adults over 19 years old who participated in the fifth Korea National Health and Nutrition Examination Survey. The user group was defined as those taking dietary supplements for more than 2 weeks during the previous year or once during the past month. Measures for the seven healthy habits were based on those included in the Alameda study and were analyzed accounting for the complex sampling design. RESULTS: The rate of taking dietary supplements was significantly higher in women, middle aged participants, urban residents, those with a higher income, those with a higher education level, and nonsmokers as well as among women with a moderate subjective health status, women who limited their alcohol content, and women with dyslipidemia. In the adjusted analysis, the rate of performing three of the 'Alameda 7' habits-eating breakfast regularly, restricting snacking, and limiting drinking-was higher in the female dietary supplement user group than in the other groups. Women practiced more healthy habits and had a higher dietary supplement intake rate than men. CONCLUSION: We found that taking dietary supplements in Korean adults is highly associated with demographic and social factors. Taking dietary supplements had a relationship with dietary habits, and there was no significant association between dietary supplement and other healthy habits. Thus in the health clinic, we suggest that taking dietary supplements complements a patient's healthy habits, with the exception of dietary habits, for health promotion.

Survivin expression and its clinical significance in pancreatic cancer.

BACKGROUND: Survivin, an inhibitor of apoptosis is expressed in several human cancers. Its expression is known to be associated with poor clinical outcome, but not widely studied in pancreatic cancer. We performed this study to determine the survivin expression in pancreatic cancer and its clinical significance as a prognostic factor. METHODS: We performed immunohistochemical staining for survivin, p53, and Bax in formalin-fixed, paraffin-embedded block from forty-nine pancreatic tissues. To determine the association with clinical course, we reviewed the patients' clinical record. RESULTS: Of the 49 cases of pancreatic cancer, 46 cases (93.9%) were positive for survivin expression. There was no significant association between survivin expression and p53 or bax. For clinicopathological parameters, perineural invasion was more common in survivin positive and venous invasion was more common in survivin negative (p = 0.041 and 0.040, respectively). Responsiveness to chemotherapy appeared to be slightly better in patients with low survivin expression. CONCLUSION: Survivin expression may be associated with venous or perineural invasion, indicating metastatic route, and seems to have a potential as a predictive marker for chemotherapy. Further study of large scale is required to determine the clinical significance of survivin expression in pancreatic cancer.

Epirubicin, cisplatin, and protracted infusion of 5-FU (ECF) in advanced intrahepatic cholangiocarcinoma.

PURPOSE: Intrahepatic cholangiocarcinoma usually presents late in the clinical course and has a poor prognosis. No effective systemic therapy is currently available. This study aimed to determine the efficacy and toxicity of the ECF regimen (epirubicin, cisplatin. and 24-h continuous infusion of 5-FU) in advanced intrahepatic cholangiocarcinoma. PATIENTS AND METHOD: On day 1, epirubicin 50 mg/m(2) and cisplatin 60 mg/m(2) were administered i.v., repeated every 21 days. 5-FU (200 mg/m(2)/day was given continuous i.v. via an ambulatory infusion pump throughout the treatment course. A total of 24 patients (15 men and nine women) with advanced intrahepatic cholangiocarcinoma between August 1996 and April 2002 were enrolled in this study. RESULTS: Of the 20 evaluable patients, two had partial response (10%) and nine had stable disease (45%), including two minor response. Grade 3/4 neutropenia was observed in six patients, while grade 3/4 thrombocytopenia was seen in five patients. There was no neutropenic infection or thrombocytopenic bleeding during any of the cycles of chemotherapy. CONCLUSION: ECF regimen is well-tolerated but is not an effective treatment for advanced intrahepatic cholangiocarcinoma. Newer clinical trials with combination drugs should be developed.

Loss of estrogen receptor-alpha expression is associated with hypermethylation near its ATG start codon in gastric cancer cell lines.

The proportion of gastric cancers positive for estrogen receptor (ER)-alpha expression is reported to be between 0-67%, depending upon the study. The role of ER-alpha in gastric carcinogenesis is unclear. The ER-alpha gene is located at chromosome 6q25.1, and the long arm of chromosome 6 has been known as a site with frequent loss of heterozygosity (LOH) in gastric cancer. ER expression is linked to suppression of cell proliferation in vitro. Epigenetic inactivation might explain the loss of ER-alpha gene expression in gastric cancer. Given there is no information available regarding the methylation status of the ER-alpha gene promoter region in gastric cancer, we investigated such methylation in 13 gastric cancer cell lines. Western blot analysis, reverse transcription-polymerase chain reaction (PCR), methylation-specific PCR (MS-PCR) and bisulfite sequencing analyses were used. ER-alpha protein was not detected in any cell line, although ER-alpha mRNA was detected in 1 of 13 gastric cancer cell lines. MS-PCR and bisulfite sequencing showed all 13 gastric cancer cell lines had methylated CpG regions in their ER-alpha gene promoters. In conclusion, inactivation of ER-alpha gene expression in gastric cancer cell lines appears associated with CpG island methylation near the TGA initiation codon of the ER-alpha gene.

Death receptor 5 and Bcl-2 protein expression as predictors of tumor response to gemcitabine and cisplatin in patients with advanced non-small-cell lung cancer.

The cytotoxic effects of gemcitabine (G) and cisplatin (C) seem to occur through induction of apoptosis. To examine whether the efficacy of GC chemotherapy might be influenced by the expression of death receptor 5 (DR5) and Bcl-2 of the tumor, we investigated the correlation between the tumor response rate and DR5 and Bcl-2 expression in a series of patients prospectively treated with GC. Thirty-four chemotherapy naïve patients with advanced non-small-cell lung cancer (NSCLC) received intravenously 1000 mg/m2 gemcitabine on d 1 and 8 along with 80 mg/m2 cisplatin on d 2, every 21 d. Tumor specimens were analyzed for DR5 and Bcl-2 expression by immunohistochemistry. The objective response rate was 56% (19 of 34 patients). With median follow-up of 10 mo, the predicted median survival time was 12 mo (95% confidence interval [CI], 9-15 mo). Eleven (32%) and 14 (41%) NSCLC cases were found positive for DR5 and Bcl-2, respectively. The response rate was significantly higher in patients with DR5 expression than those without DR5 expression (91% vs 39%; p = 0.008). Patients with Bcl-2 expression were apparently less responsive than those without Bcl-2 expression (21% vs 80%; p = 0.001). DR5 and Bcl-2 expression was significantly associated with response to GC chemotherapy. Therefore, DR5 and Bcl-2 status are useful factors for predicting the efficacy of GC.

Abdominal obesity is associated with albuminuria in women: the 2011 Korea National Health and Nutrition Examination Survey.

BACKGROUND: The effects of obesity on the kidney, apart from diabetes or hypertension, have not drawn much attention. Moreover, only a few studies have reported the relationship between obesity status and albuminuria in Asian countries, including South Korea. Therefore, this study aimed to investigate the association between obesity status and albuminuria in Korean adults. METHODS: We analyzed data from the 2011 Korea National Health and Nutrition Examination Survey. Of the 4,979 subjects included in the general-population group, 3,274 were sorted into a nondiabetic and nonhypertensive population group. Obesity status was measured by body mass index and waist circumference. Albuminuria was defined as a urine albumin-to-creatinine ratio ≥30 mg/g. RESULTS: Abdominally obese women were at higher risk for albuminuria than were women without abdominal obesity both in the general population (odds ratio [OR], 95% confidence interval [CI]: 2.08 [1.04-4.16]) and in the nondiabetic and nonhypertensive population (OR [95% CI]: 6.96 [2.34-20.64]) after further adjustment for confounders. Among generally nonobese women, abdominally obese women were at higher risk for albuminuria than were women without abdominal obesity both in the general population (OR [95% CI]: 2.82 [1.51-5.29]) and in the nondiabetic and nonhypertensive population (OR [95% CI]: 5.32 [1.47-19.22]). CONCLUSION: Abdominal obesity is associated with an increased risk for albuminuria in Korean women, independently of diabetes or hypertension. Screening for abdominal obesity, especially in women, may therefore provide earlier identification of individuals at risk for developing renal disease and cardiovascular disease, even those who are nondiabetic and nonhypertensive.

Low bone mineral density is associated with metabolic syndrome in South Korean men but not in women: The 2008-2010 Korean National Health and Nutrition Examination Survey.

UNLABELLED: We examined the relationships between bone mineral density (BMD) and metabolic syndrome in 6,659 men and 7,826 women from South Korean. After adjusting for age, body mass index (BMI), tobacco and alcohol use, and regular exercise, low BMD is especially associated with metabolic syndrome in South Korean men. PURPOSE: This study examined the relationships between BMD and metabolic syndrome (MS) in South Korean adults. METHODS: A total of 14,485 adults (6,659 men and 7,826 women) in the Korea National Health and Nutrition Examination Survey conducted from 2008 to 2010 were analyzed. We used multivariable regression models to examine the relationship between low BMD and MS. We calculated homeostasis model assessment and insulin resistance (HOMA-IR). MS was defined according to AHA/NHLBI criteria for Asians. BMD was measured at the lumbar spine (LS), femur neck (FN), total hip (TH), trochanter, and intertrochanter. RESULTS: After adjustment for age, BMI, tobacco and alcohol use, and regular exercise, the TH and FN BMD were significantly lower in men with MS than in men without MS (p < 0.05). However, there were no differences in premenopausal and postmenopausal women. In men, BMD was positively correlated with BMI, and high density lipoprotein cholesterol, but was negatively correlated with insulin, HOMA-IR, and triglyceride at all three sites (p < 0.05). Along with an increase of BMD (0.1 g/cm²), the odds ratios (ORs) for obesity and abdominal obesity were all greater than 1 at all sites in both genders. The ORs for hypertension and MS were 0.937 (0.879-0.998) and 0.899 (0.840-0.962), respectively at FN, and the OR for diabetes mellitus was 1.103 (1.017-1.196) at LS in men. In postmenopausal women, the OR for hypertension was 1.133 (1.029-1.246) at LS. CONCLUSIONS: Low BMD was especially associated with MS in South Korean men.

Estimate of a predictive cut-off value for serum 25-hydroxyvitamin D reflecting abdominal obesity in Korean adolescents.

Vitamin D deficiency is a serious global issue. Although the serum 25-hydroxyvitamin D [25(OH)D] test is generally the most accurate way to assess vitamin D levels, the optimal range of 25(OH)D has yet to be established. Moreover, the optimal level may vary according to race, region, and age. Suboptimal vitamin D status is associated with obesity and metabolic syndrome, which are the major risk factors for cardiovascular disorders; however, these relationships in children and adolescents have yet to be clearly determined. Therefore, we identified the best predictive cut-off value for reflecting abdominal obesity and, based on this value, we investigated the relationship between suboptimal 25(OH)D status and the risk for having abdominal obesity, being overweight or obese, and having metabolic syndrome in Korean adolescents. We performed a cross-sectional analysis of 713 Korean adolescents, between 12-19 years of age, and used data collected from the 2008 Korea National Health and Nutrition Examination Survey (KNHANES). Receiver operation characteristic curve analysis was used to identify the cut-off value that reflected abdominal obesity. The cut-off value of serum 25(OH)D that reflected abdominal obesity in Korean adolescents was 17.6 ng/mL. After making adjustments for gender, age, and regular physical exercise, the group that had lower levels of serum 25(OH)D compared to the cut-off value had a significantly higher risk for abdominal obesity, obesity, and metabolic syndrome than the group with 25(OH)D levels higher than the cut-off value. Suboptimal vitamin D status based on this value is associated with increased risk for abdominal obesity, obesity, and metabolic syndrome among Korean adolescents.