Further studies showed that this failure of PTH to maintain blood 1,25(OH)<sub>2</sub>D levels was associated with decreased blood levels of IGF-1, increased blood levels of FGF-23, and kidney failure.
Dysregulated actions of bone-derived phosphaturic hormone fibroblast growth factor 23 (FGF23) result in several inherited diseases, such as X-linked hypophosphatemia (XLH), and contribute substantially to the mortality in kidney failure.