Metabolism disorders of phosphorus are responsible for the onset of CKD-MBD, because reduced renal function and the accompanying phosphorus accumulation promote the secretion of fibroblast growth factor 23 (FGF23) and parathyroid hormone (PTH) and the inhibition of 1α,25-dihydroxy-vitamin D3 (1,25(OH)2D3) synthesis. Here, FGF23 is linked to chronic kidney disease.