We reported two cases of XLH and hypoparathyroidism postthyroidectomy (XLH‐HOPT) with normal TmP/GFR and with exceedingly high FGF23, both cFGF23 and iFGF23, a finding that has not been reported previously, but both cases had chronic kidney disease.(13, 14) Based on the findings of these two cases and on the observations in the literature outlined above, we sought to explore the independent effects of FGF23, PTH, and calcium on TmP/GFR. This evidence concerns the gene FGF23 and chronic kidney disease.