title: The association of serum vitamin D level with presence of metabolic syndrome and hypertension in middle-aged Korean subjects.
abstract: OBJECTIVE
  To examine the association of serum vitamin D level with metabolic syndrome (MetS) and hypertension (HTN) in middle-aged Korean subjects.
  
  
  METHODS
  We conducted a population-based, cross-sectional survey of 1330 participants aged over 40 years (median age 65.8 years) in Chungju, Korea, in 2007. The 324 subjects, who were normotensive in 2003 and who attended a follow-up visit 4 years later, were included in an analysis of the association of serum vitamin D level with the risk of HTN.
  
  
  METHODS
  Serum 25-hydroxy-vitamin D [25(OH)D] and PTH were measured in a central laboratory, using chemiluminescence assays.
  
  
  RESULTS
  The overall prevalence of the MetS in participants of this study was 45.3%. After adjusting for various covariates, subjects in the highest quintile group (61.4-116.8 nmol/l) compared with the lowest quintile group (10.0-29.7 nmol/l) of 25(OH)D had an odds ratio (OR) for having MetS of 0.35 (95% confidence intervals, CI, 0.22-0.56; P for trend <0.001). The median level of 25(OH)D was 46.8 nmol/l among 324 subjects who were normotensive in 2003. After multiple adjustment, the OR was substantially higher for new HTN (OR 2.74; 95% CI 1.40-5.34) in subjects with serum 25(OH)D levels below the median value compared with those above median. The inverse associations of vitamin D and MetS/HTN were unchanged after adjustment for PTH and serum calcium levels. There was no association between PTH and MetS.
  
  
  CONCLUSIONS
  We found a strong inverse association of 25(OH)D levels with MetS and HTN in this middle-aged Korean population. Having vitamin D deficiency was associated with an increased risk of having MetS and HTN in this demographic group.
authors.affiliation: Department of Internal Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Mee K
authors.initials: MK
authors.lastname: Kim
authors.forename: Moo
authors.initials: M
authors.lastname: Il Kang
authors.forename: Ki
authors.initials: K
authors.lastname: Won Oh
authors.forename: Hyuk S
authors.initials: HS
authors.lastname: Kwon
authors.forename: Jin H
authors.initials: JH
authors.lastname: Lee
authors.forename: Won C
authors.initials: WC
authors.lastname: Lee
authors.forename: Kun-Ho
authors.initials: KH
authors.lastname: Yoon
authors.forename: Ho Y
authors.initials: HY
authors.lastname: Son
mesh_terms: D000368:Aged; D002118:Calcium / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000453:epidemiology; D007723:Korea / Q000453:epidemiology; D016015:Logistic Models; D008163:Luminescent Measurements / Q000379:methods; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood* / Q000453:epidemiology; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010281:Parathyroid Hormone / Q000097:blood; D015995:Prevalence; D014807:Vitamin D / Q000097:blood*
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; D002118:Calcium