In vitro studies in cultured rat calvaria demonstrated that 1,25(OH)2D increased FGF‐23.14 In addition, it was reported that that FGF‐23 synthesis in rat calvaria was upregulated by 1,25(OH)2D.14 Therefore, the likely explanation for the markedly elevated blood levels of FGF‐23 in our patient is his elevated 1,25(OH)2D level, which in turn was stimulating the osteocytes and osteoblasts to produce this phosphate‐regulating hormone, resulting in hypophosphatemia (Figs. 2, 4). Here, FGF23 is linked to hypophosphatemia.