CYP27B1 and chronic kidney disease: To determine the downstream effects of lowered iFGF23 on 1,25D metabolism, kidney Cyp27b1 and Cyp24a1 gene expression was measured, and showed that although modestly elevated, there was no statistical difference in Cyp27b1 expression between casein‐saline and CKD‐saline groups; EPO treatment significantly elevated Cyp27b1 expression in the mice with CKD (Figure 2c).