From CKD stage 3A onward, increasingly elevated levels of intact FGF23 (iFGF23) (z-score: 0.49), and parathyroid hormone (PTH) (z-score: 1.68) were observed, as well as reduced levels of soluble Klotho (sKlotho) (z-score: -0.66). Here, FGF23 is linked to chronic kidney disease.