FGF23 and chronic kidney disease: As the first investigation in experimental CKD to assess the daily variations in these factors, this study was able to demonstrate that: (i) renal phosphate handling does not appear to be the dominant component in these daily variations, (ii) severe hyperphosphatemia in CKD is associated with altered phosphate, calcium, and PTH variability, and (iii) VC significantly decreases the daily oscillations of circulating phosphate and FGF‐23, while increasing the variation in PTH.