Cholecalciferol, calcitriol, and vascular function in CKD a randomized, double-blind trial

Abstract

Background and objectives Highcirculating vitaminDlevels are associated with lower cardiovascularmortality in CKD, possibly by modifying endothelial function. We examined the effect of calcitriol versus cholecalciferol supplementation on vascular endothelial function in patients with CKD. Design, setting, participants, &measurementsWeperformed a prospective, double-blind, randomized trial of 128 adult patients with eGFR=15–44 ml/min per 1.73 m2and serum 25-hydroxyvitamin D level, 30 ng/ml at the University of Colorado. Participants were randomly assigned to oral cholecalciferol (2000 IU daily) or calcitriol (0.5mg)dailyfor 6months.Theprimaryendpointwas change inbrachial arteryflow-mediateddilation.Secondary end points included changes in circulatingmarkers of mineralmetabolismand circulating and cellular markers of inflammation. ResultsOne hundred and fifteen patients completed the study. The mean (SD) age and eGFR of participantswere 58±12 years old and 33.0±10.2 ml/min per 1.73 m2, respectively. There were no significant differences between groups at baseline. After 6 months, neither calcitriol nor cholecalciferol treatment resulted in a significant improvement in flow-mediated dilation (mean±SD percentage flow-mediated dilation; calcitriol: baseline 4.8±3.1%, end of study 5.1±3.6%; cholecalciferol: baseline 5.2±5.2%, end of study 4.7±3.6%); 25-hydroxyvitamin D levels increased significantly in the cholecalciferol group compared with the calcitriol group (cholecalciferol: 11.0±9.5 ng/ml; calcitriol: 20.8±4.8 ng/ml; P, 0.001). Parathyroid hormone levels decreased significantly in the calcitriol group compared with the cholecalciferol group (median [interquartile range]; calcitriol: 222.1 [248.7–3.5] pg/ml; cholecalciferol: 20.3 [222.6–16.9] pg/ml; P=0.004). Conclusions Sixmonths of therapywith calcitriol or cholecalciferol did not improve vascular endothelial function or improve inflammation in patients with CKD.