Uremia-dependent impairment of 1,25-dihydroxyvitamin D production also in extrarenal cells, uremia-dependent impairment of 25-hydroxyvitamin D uptake and intracellular transport in those cells, the reduced expression of vitamin D receptor protein in CKD, and the disturbed interaction of vitamin D receptors with DNA in uremia can contribute to the lesser than expected effects of vitamin D therapy in CKD (for review of mechanisms see [191, 192]). Here, VDR is linked to chronic kidney disease.