The Metabolic Syndrome and Carotid Intima-Media Thickness in Relation to the Parathyroid Hormone to 25-OH-D(3) Ratio in a General Population

BackgroundParathyroid 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-D(3) might be associated with the metabolic syndrome (MS) and arterial calcification.MethodsIn 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-D(3), 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.ResultsThe 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-D(3) 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-D(3), the regression coefficients relating CIMT to PTH/25-OH-D(3) ratio and MS were +51 microm (P = 0.013) and +19 microm (P = 0.45), respectively. Multivariable-adjusted analyses were confirmatory.ConclusionsMS prevalence and CIMT were positively associated with PTH/25-OH-D(3). CIMT was not associated with MS. Prospective studies and intervention trials should address the causality of these associations.American Journal of Hypertension (2010). doi:10.1038/ajh.2010.124.status: publishe