ABSTRACT
Objective: To investigate the possible correlation between serum 25-hydroxyvitamin D levels and resistant hypertension [RH]
Subjects and Methods: Patients who had undergone ambulatory blood pressure measurements [ABPM] during outpatient controls were enrolled. Fifty subjects with RH, 50 with controlled hypertension [CHT] and 50 normotensive subjects [NT] were included in the study. RH was defined as 'suboptimal blood pressure control despite using 3 antihypertensive agents including a diuretic or need for 4 or more drugs to control blood pressure'. The 25-hydroxyvitamin D and parathormone levels were compared between the groups. Pearson's correlation coefficient test was applied to assess the correlation between 25-hydroxyvitamin D levels and office blood pressure [BP] and ABPM. Logistic regression analysis was used to determine the independent correlates of RH
Results: The 25-hydroxyvitamin D level was significantly lower in the RH group [17.02 +/- 5.4 ng/ml] compared to the CHT [24.9 +/- 4.8 ng/ml] and NT groups [28.0 +/- 5.7 ng/ml, p < 0.001]. In univariate correlation analysis, 25-hydroxyvitamin D levels had a significant negative correlation with office systolic BP [r = -0.329, p < 0.001], office diastolic BP [r = -0.395, p < 0.001], systolic ambulatory BP [r = -0.844, p = 0.004], and diastolic ambulatory BP [r = -0.567, p = 0.005]. ROC analysis revealed that 25-hydroxyvitamin D levels <21.50 ng/ml predicted the presence of RH with a sensitivity of 78% and a specificity of 79% [AUC = 0.89, 95% CI 0.83-0.94]. In the multivariate logistic regression analysis, 25-hydroxyvitamin D level was independently correlated with the presence of RH [beta 0.660, 95% CI 0.572-0.760, p < 0.001]
Conclusion: There was an independent correlation between lower 25-hydroxyvitamin D levels and presence of RH