title: Changes in fibroblast growth factor 23 during treatment of secondary hyperparathyroidism with alfacalcidol or paricalcitol.
abstract: BACKGROUND
  Fibroblast growth factor 23 (FGF23) increases renal phosphate excretion and decreases the formation of 1,25 dihydroxyvitamin D. In patients with chronic kidney disease, plasma FGF23 levels are markedly elevated by unknown mechanisms. We explored the changes in FGF23 during treatment of secondary hyperparathyroidism (SHPT) with alfacalcidol or paricalcitol in haemodialysis patients.
  
  
  METHODS
  Intravenous alfacalcidol and paricalcitol were compared in haemodialysis patients with SHPT in a randomized 2 × 16-week cross-over study, with 6 weeks washout period preceding treatment and between treatment periods. In 57 of the enrolled patients, blood samples were frozen before and after each treatment period and available for measurement of FGF23.
  
  
  RESULTS
  Treatment with both analogues increased FGF23 (P < 0.05 in all treatment periods). The magnitude of increase was similar for alfacalcidol and paricalcitol (Period 1: 223 versus 314%; P = 0.384 and Period 2: 174 versus 227%; P = 0.510) and the levels returned to pre-treatment levels during the washout period. Independent predictors of rise in FGF23 were baseline levels of FGF23 (P < 0.01), changes in ionized calcium (P < 0.01) and phosphate (P < 0.01) and cumulative dose of vitamin D analogues (P = 0.024).
  
  
  CONCLUSIONS
  Alfacalcidol and paricalcitol increase the plasma levels of FGF23 equally and substantially in haemodialysis patients.
authors.affiliation: Department of Medicine, Roskilde Hospital, Roskilde, Denmark. dittehansen@dadlnet.dk
authors.forename: Ditte
authors.initials: D
authors.lastname: Hansen
authors.forename: Knud
authors.initials: K
authors.lastname: Rasmussen
authors.forename: Susanne M
authors.initials: SM
authors.lastname: Pedersen
authors.forename: Lars M
authors.initials: LM
authors.lastname: Rasmussen
authors.forename: Lisbet
authors.initials: L
authors.lastname: Brandi
mesh_terms: D000368:Aged; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D002118:Calcium / Q000097:blood; D018592:Cross-Over Studies; D004872:Ergocalciferols / Q000627:therapeutic use*; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D006801:Humans; D006887:Hydroxycholecalciferols / Q000627:therapeutic use*; D006962:Hyperparathyroidism, Secondary / Q000188:drug therapy* / Q000378:metabolism*; D007676:Kidney Failure, Chronic / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood; D006435:Renal Dialysis
chemical_list: D050071:Bone Density Conservation Agents; D004872:Ergocalciferols; C000717427:FGF23 protein, human; D006887:Hydroxycholecalciferols; D010281:Parathyroid Hormone; D010710:Phosphates; D005346:Fibroblast Growth Factors; C084656:paricalcitol; D000089703:Fibroblast Growth Factor-23; D002118:Calcium; C008088:alfacalcidol