FGF-23 and PTH in Hemodialysis Patients

In this pilot study the investigator will examine the levels of fibroblast growth factor (FGF-23) and parathyroid hormone (PTH) levels during hemodialysis therapy in 30 patients and assess the correlation between these parameters and the T-50 calcification propensity, as well as further parameters of secondary hyperparathyroidism (sHPT), like serum calcium (sCa), phosphate (P), 25-hydroxy-vitamin D (25(OH)D) and 1,25 dihydroxy-vitamin D (1,25(OH)2D). The investigator hypothesize that FGF-23 and PTH levels are at their highest at the beginning of dialysis and decrease during the treatment.