In the frame of a randomized, double-blind, placebo controlled trial, the Paracalcitol and ENdothelial fuNction in chronic kidneY disease (PENNY), we investigated whether vitamin D receptor activation by paricalcitol (2 μg/day x 12 weeks) affects the plasma concentration of ADMA and symmetric dimethyl arginine (SDMA) in 88 patients with stage 3 to 4 CKD. Here, VDR is linked to chronic kidney disease.