Background/Aims: Hypovitaminosis D is highly prevalent among patients with chronic kidney disease (CKD) and has been associated with poor outcome. We aimed to test the effect of a protocol of cholecalciferol supplementation on the restoration of vitamin D status and on parathyroid hormone (PTH) levels in patients with CKD. Methods: This was a prospective interventional study of 6 months. Forty-five CKD patients (stages 3 and 4) with 25-hydroxyvitamin D deficiency [25(OH)D <15 ng/ml] were included. Patients received a weekly dose of 50,000 IU of cholecalciferol during 3 months, and 50,000 IU/month thereafter for those who had achieved 25(OH)D ≥30 ng/ml. Results: At 3 months, 78% of the patients restored their vitamin D status. At 6 months, only 43% of those patients maintained adequate vitamin D status. PTH decreased at 3 months (p = 0.02) but returned to baseline levels after 6 months. Fibroblast growth factor 23 increased at 3 months (p = 0.001) and returned to initial levels at 6 months. No changes were found in serum 1,25(OH)2D, ionized calcium and phosphorus. Conclusions: A weekly dose of 50,000 IU of cholecalciferol for 3 months restored the vitamin D status of most patients and led to a reduction in PTH. The monthly dose of 50,000 IU appears not to be sufficient to maintain the levels of 25(OH)D.
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.
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