Vitamin D, Parathyroid Hormone and Their Associations with Hypertension in a Chinese Population

Background: Conflicting reports support or refute an association between vitamin D deficiency with high levels of parathyroid hormone (PTH) and raised blood pressure or hypertension. Objective: To explore the associations of serum vitamin D and PTH levels with blood pressure and risk of hypertension in a Chinese population. Methods: A population-based cross-sectional study was conducted among 1,420 Chinese participants, aged 20-83 years, in 2010. Anthropometric phenotypes and blood pressure were evaluated. Serum lipids, 25-hydroxyvitamin D [25(OH) D] and PTH were measured. Results: One thousand four hundred and twenty participants, including 566 women (39.9%), were evaluated in 2010. Four hundred and eighty seven were hypertensive (34.3%), of whom 214 (43.9%) received antihypertensive treatment. The median concentrations of serum 25(OH) D and PTH were 22.0 ng/ml and 2.83 pmol/l, respectively. Serum 25(OH) D and natural log of PTH levels were not independently associated with blood pressure in a multivariable adjusted linear regression analysis of 1,206 participants not receiving antihypertensive treatment (P>0.05). In logistic regression analyses, serum 25(OH) D levels were not associated with risk of hypertension in single and multiple regression models. One unit increments of natural log of PTH levels were significantly associated with risk of hypertension in the crude model (OR = 1.78, 95% confidence interval 1.38-2.28, P<0.0001) and model adjusted for age and sex (OR = 1.41, 95% confidence interval 1.08-1.83, P = 0.01). However, these associations were attenuated and became nonsignificant (OR = 1.29, 95% confidence interval 0.98-1.70, P = 0.07) after further adjustment for body mass index, current alcohol intake, current smoking, glomerular filtration rate and family history of hypertension. Conclusions: Serum vitamin D and PTH levels are not independently associated with blood pressure or risk of hypertension in a Chinese population.