That serum phosphate levels alone are not a good index of altered phosphate homeostasis is also highlighted by the finding that vascular calcification can occur in early CKD when phosphate levels are normal or near normal [4], and by the finding that fibroblast growth factor 23 (FGF-23) [5] and Klotho [6] may change even earlier in CKD, possibly independent of phosphate, and are potential predictors of vascular calcification and mortality in their own right. The gene discussed is FGF23; the disease is chronic kidney disease.