[FGF-23 and Klotho protein - new markers in chronic kidney disease?].

Disorders of calcium and phosphate metabolism are among the major problems in patients with chronic kidney disease (CKD), especially undergoing chronic dialysis. Besides the classic parathyroid-kidney axis, in recent years the existence of an endocrinological bone-kidney axis has been established, which allows better explanation of calcium and phosphate metabolism pathophysiology and secondary hyperparathyroidism in CKD. Fibroblast growth factor 23 (FGF-23) and its co-factor alpha-Klotho protein are the most important factors in the axis. The role of FGF-23 and Klotho protein, their mechanisms of action and significance in CKD have been presented. In ealy stages of CKD the increase of FGF-23 level precedes the decline in vitamin 1.25 (OH)2D3 and the increase of PTH level. Some studies showed correlation between the elevated FGF-23 level and increased mortality from cardiovascular disease in patients with chronic kidney disease. Clinical usefulness of determinations of FGF-23 and Klotho protein in chronic kidney disease is currently investigated.