title: Pretreatment serum FGF-23 levels predict the efficacy of calcitriol therapy in dialysis patients.
abstract: BACKGROUND
  The predictor for the result of calcitriol therapy would be useful in the clinical practice of secondary hyperparathyroidism. Fibroblast growth factor-23 (FGF-23) is a newly found circulating phosphaturic factor. Its circulating level is elevated in uremia.
  
  
  METHODS
  Dialysis patients with plasma intact parathyroid hormone (iPTH) levels greater than 300 pg/mL were included in the study. Calcitriol was intravenously injected three times a week. The patients whose plasma iPTH levels dropped below 300 pg/mL within 24 weeks were defined as those who had been successfully treated. A sandwich enzyme-linked immunosorbent assay (ELISA) system that detects human FGF-23 was applied.
  
  
  RESULTS
  Sixty-two patients were analyzed. The pretreatment FGF-23 levels were related to the iPTH levels, calcium x phosphate product levels, and history of active vitamin D therapy. The pretreatment FGF-23, iPTH, and calcium levels were lower in the patients who would be successfully treated with calcitriol. A logistic regression study revealed that the pretreatment iPTH and FGF-23 levels significantly affected the therapy results. Analyses using a receiver-operated curve revealed that FGF-23 was the best screening test for identifying patients with future refractory response to calcitriol therapy. The treatment would be successful in 88.2% of those with FGF-23 </=9860 ng/L and iPTH </=591 pg/mL, while it would be successful in only 4.2% of those with FGF-23 >9860 ng/L and iPTH >591 pg/mL.
  
  
  CONCLUSIONS
  Pretreatment serum FGF-23 levels were a good indicator in predicting the response to calcitriol therapy. The measurement of serum FGF-23 levels, especially in combination with iPTH levels, is a promising laboratory examination for the clinical practice of secondary hyperparathyroidism.
authors.affiliation: Division of Clinical Nephrology and Rheumatology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan. jjkaz@med.niigata-u.ac.jp
authors.forename: Junichiro J
authors.initials: JJ
authors.lastname: Kazama
authors.forename: Fuminori
authors.initials: F
authors.lastname: Sato
authors.forename: Kentaro
authors.initials: K
authors.lastname: Omori
authors.forename: Hitomi
authors.initials: H
authors.lastname: Hama
authors.forename: Suguru
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Hiroki
authors.initials: H
authors.lastname: Maruyama
authors.forename: Ichiei
authors.initials: I
authors.lastname: Narita
authors.forename: Fumitake
authors.initials: F
authors.lastname: Gejyo
authors.forename: Takeyoshi
authors.initials: T
authors.lastname: Yamashita
authors.forename: Seiji
authors.initials: S
authors.lastname: Fukumoto
authors.forename: Masafumi
authors.initials: M
authors.lastname: Fukagawa
mesh_terms: D002117:Calcitriol / Q000627:therapeutic use*; D002118:Calcium / Q000097:blood; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D006801:Humans; D016015:Logistic Models; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood; D006435:Renal Dialysis
chemical_list: C000717427:FGF23 protein, human; D010281:Parathyroid Hormone; D010710:Phosphates; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D002117:Calcitriol; D002118:Calcium