FGF23 and chronic kidney disease: In this regard, we previously demonstrated that anemia in WT mice and a mouse line carrying an ADHR FGF23 stabilizing mutation responded to iron deficiency anemia (IDA) by increasing Fgf23 mRNA.3 Anemia is also very common in CKD, where 75% of patients by disease stage 4-5 have anemia and concomitant marked elevations in FGF23.