The 1,25(OH)2D, CaSR and VDR expression levels in the PTGs, which suppress parathyroid cell proliferation, were not significantly different between the CKD NP and CKD HP groups; however, FGF23, which also suppresses parathyroid cell proliferation [43, 44], was significantly increased in the CKD HP group. The gene discussed is FGF23; the disease is chronic kidney disease.