title: The metabolic syndrome and carotid intima-media thickness in relation to the parathyroid hormone to 25-OH-D(3) ratio in a general population.
abstract: BACKGROUND
  Parathyroid hormone (PTH) and vitamin D interactively regulate calcium fluxes across membranes, and thereby modulate insulin sensitivity, blood pressure, and arterial calcification. We hypothesized that lower calcium intake as reflected by circulating PTH and 25-OH-D₃ might be associated with the metabolic syndrome (MS) and arterial calcification.
  
  
  METHODS
  In a random population sample (n = 542; 50.5% women; mean age, 49.8 ± 13.1 years), we measured MS prevalence (International Diabetes Federation (IDF) and American Heart Association (AHA) criteria), PTH and 25-OH-D₃, serum and 24-h urinary calcium, MS components, carotid intima-media thickness (CIMT), and calcium intake from dairy products. We assessed associations in multivariable-adjusted analyses, using linear and logistic regressions.
  
  
  RESULTS
  The prevalence of MS was 21.0% (IDF criteria) and 23.6% (AHA criteria). MS prevalence, blood pressure, waist circumference, body mass index, fasting blood glucose, insulin and triglycerides, and CIMT increased (P ≤ 0.042) across quartiles of the PTH/25-OH-D₃ ratio, whereas serum and 24-h urinary calcium decreased (P ≤ 0.029). Waist circumference and fasting blood glucose decreased across quartiles of habitual calcium intake (P ≤ 0.04). In models that included MS (IDF) and PTH/25-OH-D₃, the regression coefficients relating CIMT to PTH/25-OH-D₃ ratio and MS were +51 µm (P = 0.013) and +19 µm (P = 0.45), respectively. Multivariable-adjusted analyses were confirmatory.
  
  
  CONCLUSIONS
  MS prevalence and CIMT were positively associated with PTH/25-OH-D₃. CIMT was not associated with MS. Prospective studies and intervention trials should address the causality of these associations.
authors.affiliation: Department of Epidemiology, Maastricht University, The Netherlands. tom.richart@epid.unimaas.nl
authors.forename: Tom
authors.initials: T
authors.lastname: Richart
authors.forename: Lutgarde
authors.initials: L
authors.lastname: Thijs
authors.forename: Tim
authors.initials: T
authors.lastname: Nawrot
authors.forename: Jin
authors.initials: J
authors.lastname: Yu
authors.forename: Tatiana
authors.initials: T
authors.lastname: Kuznetsova
authors.forename: Elisabeth J
authors.initials: EJ
authors.lastname: Balkestein
authors.forename: Harry A
authors.initials: HA
authors.lastname: Struijker-Boudier
authors.forename: Jan A
authors.initials: JA
authors.lastname: Staessen
mesh_terms: D000328:Adult; D000368:Aged; D002112:Calcifediol / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood / Q000209:etiology* / Q000473:pathology; D008875:Middle Aged; D015999:Multivariate Analysis; D010281:Parathyroid Hormone / Q000097:blood*; D017539:Tunica Intima / Q000473:pathology*; D017540:Tunica Media / Q000473:pathology*
chemical_list: D010281:Parathyroid Hormone; D002112:Calcifediol