25-Hydroxyvitamin D and Parathyroid Hormone Are Not Associated With Carotid Intima-Media Thickness or Plaque in the Multi-Ethnic Study of Atherosclerosis

Objective Observational evidence supports independent associations of 25-hydroxyvitamin D (25-OHD) and parathyroid hormone (PTH) with cardiovascular risk. A plausible hypothesis for these associations is accelerated development of atherosclerosis. Approach and Results We evaluated cross-sectional and longitudinal associations of 25-OHD and PTH with carotid intima-media thickness (IMT) and carotid plaques among 3251 participants free of cardiovascular disease in the Multi-Ethnic Study of Atherosclerosis. 25-OHD and PTH were measured at baseline by mass spectrometry and immunoassay, respectively. All subjects underwent a carotid ultrasound examination at baseline and 9.4 years later (median, range 8-11.1 years). Multivariable linear and logistic regressions were used to test associations of 25-OHD and PTH with the extent and progression of IMT and the prevalence and incidence of carotid plaque. Mean (SD) 25-OHD and PTH were 25.8 ng/mL (10.6) and 44.2 pg/mL (20.2), respectively. No independent associations were found between 25-OHD or PTH and IMT at baseline (increment of 1.9 m [95% confidence interval, -5.1 to 8.9] per 10 ng/mL lower 25-OHD; increment of 0.8 m [95% confidence interval, -3.2 to 4.8] per 10 pg/mL higher PTH) or progression of IMT (increment of 2.6 m [95% confidence interval, -2.5 to 7.8] per 10 ng/mL lower 25-OHD, increment of 1.6 m [95% confidence interval, -1.9 to 5.2] per 10 pg/mL higher PTH). No associations were found with the baseline prevalence of carotid plaque or the incidence of new plaques during the study period. We did not observe any interaction by race or ethnicity (White, Chinese, Black, and Hispanic). Conclusions The consistent lack of association of vitamin D and PTH with carotid IMT and plaque suggests that these hormones may influence cardiovascular risk through pathways not reflected by carotid atherosclerosis.