FGF23 and chronic kidney disease: Serum creatinine, systolic blood pressure (SBP), and phosphatonins (FGF23, PTH, Klotho, and 25(OH)D) were higher in the CKD group than in the CTL group (p < 0.05), but there was no significant difference in serum phosphate and serum calcium between CTL and CKD groups (Table 1).