Effects of Cholecalciferol on Osteoprotegerin Levels in Patients on Peritoneal Dialysis

Patients with chronic kidney disease on peritoneal dialysis have very low 25-(OH) vitamin D levels. Vitamin D deficiency may be involved in generalized atherosclerosis, vascular calcification and cardiovascular mortality. Among others, Osteoprotegerin (OPG) has been implicated in the pathogenesis leading up vessel calcification in this patients. Furthermore, very low levels of 25-(OH) vitamin D in peritoneal dialysis patients are associated with increased levels of OPG and high values of vascular calcification scores in x-rays. It is unknown whether cholecalciferol supplementation in patients on peritoneal dialysis with low levels of 25-(OH) vitamin D could change the proteins associated with vascular calcification. The objective is to conduct a randomized, double-blind, placebo-controlled study focusing on the impact of Cholecalciferol substitution in 25-OH vitamin D deficient peritoneal dialysis patients on circulating OPG and other osteogenic biomarkers levels during 16 weeks of intervention. Moreover, the impact of cholecalciferol on serum calcium and phosphorus levels, Kidney Disease Quality of Life Short Form, and ultrasound characteristics of carotid arterial will be performed during the first four weeks after inclusion, and after 28 weeks postintervention. Peritoneal dialysis patients found to have 25-(OH) vitamin D levels \<20 ng/ml will be included and will be randomized to receive either oral cholecalciferol therapy or placebo. Cholecalciferol will be administered at a daily dose of 4800 IU over a time period of 16 weeks. All in all, 58 subjects will be included in this study.