Severe hypovitaminosis D in chronic kidney disease: association with blood pressure and coronary artery calcification

Hypovitaminosis D occurs early in the course of chronic kidney disease (CKD), and its association with cardiovascular morbidity and mortality is well known. In this study, we aimed to evaluate whether the degree of hypovitaminosis D may differently affect blood pressure (BP) and coronary artery calcification (CAC) in nondialyzed CKD patients. This study included 80 CKD patients with a creatinine clearance between 15 and 60 ml/min/1.73 m 2 and serum 25 hydroxivitamin D [25(OH)D] level <30 ng/ml. Patients underwent 24-h ambulatory BP monitoring, evaluation of CAC (multi-slice computed tomography), and laboratory evaluation. Two groups, based on the degree of hypovitaminosis D, were defined according to the median 25(OH)D value. Patients with severe hypovitaminosis D [25(OH)D <17.2 ng/ml; S-group) exhibited a higher systolic BP at all time periods (24-h, nighttime, daytime) when compared to patients with mild hypovitaminosis D [25(OH)D >17.2 ng/ml; M-group]. No differences were found between the S and M-group in terms of diastolic BP and the presence of coronary calcification. In the multiple linear regression analysis, severe hypovitaminosis D was a predictor of 24-h, daytime and nighttime BP after controlling for a number of confounders. The severity of hypovitaminosis D was associated with increased BP in nondialyzed CKD patients. The degree of hypovitaminosis D was not related to CAC, which was equally elevated in both the severe and mild hypovitaminosis D groups.