title: Serum fibroblast growth factor-23 levels predict the future refractory hyperparathyroidism in dialysis patients.
abstract: BACKGROUND
  Secondary hyperparathyroidism is a common complication among long-term dialysis patients. The method of predicting future parathyroid function has not yet been established. Fibroblast growth factor-23 (FGF-23) is a newly found humoral phosphaturic factor.
  
  
  METHODS
  One hundred and three nondiabetic dialysis patients whose plasma intact parathyroid hormone (PTH) levels were below 300 pg/mL were included in the study. Blood samples were stored at -80 degrees C for 2 years. Meanwhile, each physician in charge decided upon the strategy of medical therapy for maintaining intact PTH levels between 150 and 300 pg/mL. Patients were judged 2 years after the sample collection with regard to whether the hyperparathyroidism responded to the medical therapy. The definition of refractory secondary hyperparathyroidism was either (1) retaining intact PTH levels greater than 300 pg/mL 2 years after sample collection, or (2) having received the parathyroid intervention therapy during the observation period. Serum FGF-23 levels were determined with a sandwich enzyme-linked immunosorbent assay system that detects biologically active human FGF-23.
  
  
  RESULTS
  Seventeen patients with intact PTH levels greater than 300 pg/mL were judged as having secondary hyperparathyroidism refractory to medical therapy. A stepwise regression analysis revealed that only serum levels of FGF-23 were significantly related to the prognosis of parathyroid function. A receiver-operated characteristic analysis demonstrated that the area under the curves obtained from FGF-23 (7099.9) was significantly greater than that obtained from intact PTH (6306.4, P < .01) and Ca x Pi (5670.3, P <.0001). Although the plasma intact PTH levels at the beginning of the observation period were comparable to each other, the intact PTH levels at 2 years after the sample collection were significantly higher in the patients with FGF-23 >/=7500 ng/L than in those with FGF-23 <7500 ng/L (P < .0001).
  
  
  CONCLUSIONS
  Serum FGF-23 level was found to be the most useful factor in predicting future development of refractory secondary hyperparathyroidism in long-term dialysis patients with mild secondary hyperparathyroidism. The measurement of serum FGF-23 levels is a promising laboratory examination that can be applied in the clinical practice of uremic secondary hyperparathyroidism.
authors.affiliation: Division of Nephrology and Dialysis Center, Kobe University School of Medicine, Kobe, Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Nakanishi
authors.forename: Junichiro James
authors.initials: JJ
authors.lastname: Kazama
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nii-Kono
authors.forename: Kentaro
authors.initials: K
authors.lastname: Omori
authors.forename: Takeyoshi
authors.initials: T
authors.lastname: Yamashita
authors.forename: Seiji
authors.initials: S
authors.lastname: Fukumoto
authors.forename: Fumitake
authors.initials: F
authors.lastname: Gejyo
authors.forename: Takashi
authors.initials: T
authors.lastname: Shigematsu
authors.forename: Masafumi
authors.initials: M
authors.lastname: Fukagawa
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000097:blood / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D006435:Renal Dialysis / Q000009:adverse effects*
chemical_list: C000717427:FGF23 protein, human; D010281:Parathyroid Hormone; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23