Cholecalciferol supplementation in chronic kidney disease: restoration of vitamin d status and impact on parathyroid hormone

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)(2)D, 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.