While the effects of FGF23 on mineral metabolism in CKD appears to be similar to its effects in individuals with normal kidney function, elevated levels of the protein in the CKD population have also been linked to kidney disease progression, altered skeletal histology, and increased mortality rates, relationships that have not been examined in the general population. Thus, potential differences in FGF23 metabolism accompany the elevated levels found in CKD patients and, although the exact pathophysiological consequences remain mostly unknown, elevated FGF23 levels appear to contribute to major complications of CKD that plague both adults and children.