FGF23 and rickets: X‐linked hypophosphatemic rickets (XLH; OMIM# 307800) caused by inactivating mutations in PHEX (phosphate‐regulating endopeptidase homolog, X‐linked), is the most common form of inherited rickets at approximately 1:20,000 births.(1, 2) XLH is characterized by renal phosphate wasting caused by increased fibroblast growth factor 23 (FGF23), leading to inappropriately low 1,25‐dihydroxyvitamin D and hypophosphatemia, contributing to mineralization disturbances.