Paricalcitol and endothelial function in chronic kidney disease trial

Altered vitamin D metabolism and low levels of the active form of this vitamin, 1,25-dihydroxy-vitamin D, is a hallmark of chronic kidney disease (CKD), but there is still no randomized controlled trial testing the effect of active forms of vitamin D on vascular function in patients with CKD. Paricalcitol and ENdothelial fuNction in chronic kidneY disease (PENNY) is a double-blinded randomized controlled trial (ClinicalTrials.gov, NCT01680198) testing the effect of an active form of vitamin D, paricalcitol (2 μg/d×12 weeks) on endothelium-dependent and endothelium-independent vasodilatation in 88 patients with stage 3 to 4 CKD and parathormone >65 pg/mL (paricalcitol, n=44; placebo, n=44). Paricalcitol treatment reduced parathormone (-75 pg/mL; 95% confidence interval, -90 to -60), whereas parathormone showed a small rise during placebo (21 pg/mL; 95% confidence interval, 5-36). Blood pressure did not change in both study arms. Baseline flow-mediated dilation was identical in patients on paricalcitol (3.6±2.9%) and placebo (3.6±2.9%) groups. After 12 weeks of treatment, flow-mediated dilation rose in the paricalcitol but not in the placebo group, and the betweengroup difference in flow-mediated dilation changes (the primary end point, 1.8%; 95% confidence interval, 0.3-3.1%) was significant (P=0.016), and the mean proportional change in flow-mediated dilation was 61% higher in paricalcitoltreated patients than in placebo-treated patients. Such an effect was abolished 2 weeks after stopping the treatment. No effect of paricalcitol on endothelium-independent vasodilatation was registered. Paricalcitol improves endotheliumdependent vasodilatation in patients with stage 3 to 4 CKD. Findings in this study support the hypothesis that vitamin D may exert favorable effects on the cardiovascular system in patients with CKD.