The metabolic syndrome and carotid intima-media thickness in relation to the parathyroid hormone to 25-OH-D3 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-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-D3, the regression coefficients relating CIMT to PTH/25-OH-D3 ratio and MS were 51νm (P =0.013) and 19νm (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. © 2011 American Journal of Hypertension, Ltd.