CASR and parathyroid hyperplasia: Downregulation of VDR is associated with PTG hyperplasia.39,185 The pathologic sequence of events as illustrated in Figure 11A and B occur nearly identically in parathyroid cells and many kidney cells including podocytes.40 The CaR is decreased in hyperplastic parathyroid cells due to lack of VDR needed for its induction by calcitriol.23,186 Rescue of PTH control with calcitriol treatment during CKD is more difficult as parathyroid hyperplasia advances due to downregulation of both VDR and CaR.