title: Changes in plasma FGF23 in growth hormone deficient children during rhGH therapy.
abstract: BACKGROUND
  Children with growth hormone deficiency (GHD) have increased renal phosphorus reabsorption during rhGH therapy, Fibroblast growth factor 23 (FGF23) is a known regulator of serum phosphorus and may be responsible for this effect.
  
  
  METHODS
  Prospective study in GHD children investigating changes in plasma C-terminal FGF23 (C-FGF23), markers of mineral metabolism, and insulin-like growth factor (IGF-1) in the first year of rhGH therapy. Normal stature children served as baseline controls.
  
  
  RESULTS
  The two groups at baseline were similar, except GHD patients had lower baseline TmP/GFR vs. controls (p < 0.05). C-FGF23 in GHD patients trended upward at follow-up 1 (p = 0.058) and significantly increased at follow-up 2 (p = 0.0005) compared to baseline. TmP/GFR also rose at follow-up 1 (p = 0.002) and follow-up 2 (p = 0.027). The C-FGF23 rise persisted after adjusting for age, gender, sex, total calcium, and phosphorus (p < 0.01) but attenuated after adjusting for TmP/GFR or IGF-1.
  
  
  CONCLUSIONS
  C-FGF23 rises during rhGH therapy in spite of increased Tmp/GFR, an unanticipated observation given the role of FGF23 as a phosphaturic factor. The C-FGF23 rise may be a secondary response during rhGH therapy.
authors.affiliation: Department of Pediatrics, Division of Pediatric Endocrinology, University of Alabama at Birmingham School of Medicine, Birmingham, AL, USA. jgardner@peds.uab.edu
authors.forename: James
authors.initials: J
authors.lastname: Gardner
authors.forename: Ambika
authors.initials: A
authors.lastname: Ashraf
authors.forename: Zhiying
authors.initials: Z
authors.lastname: You
authors.forename: Kenneth
authors.initials: K
authors.lastname: McCormick
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D002118:Calcium / Q000097:blood; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D005500:Follow-Up Studies; D006130:Growth Disorders / Q000097:blood* / Q000188:drug therapy*; D019382:Human Growth Hormone / Q000172:deficiency* / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D010758:Phosphorus / Q000097:blood; D011446:Prospective Studies
chemical_list: D015415:Biomarkers; C000717427:FGF23 protein, human; D019382:Human Growth Hormone; D010758:Phosphorus; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D002118:Calcium