title: Lack of FGF23 response to acute changes in serum calcium and PTH in humans.
abstract: BACKGROUND
  1,25-Dihydroxyvitamin D (1,25D) administration and long-term increases in phosphate, PTH, and calcium concentrations are associated with increases in circulating fibroblast growth factor 23 (FGF23); however, whether or not acute changes in serum calcium modulate short-term FGF23 release is unknown.
  
  
  OBJECTIVE
  To assess the direct effect of acute changes in calcium and PTH on circulating FGF23 levels.
  
  
  METHODS
  A university clinical and translational research center.
  
  
  METHODS
  Twelve healthy volunteers and 10 dialysis patients.
  
  
  METHODS
  Calcium gluconate and sodium citrate were infused for 120 minutes on 2 consecutive days.
  
  
  METHODS
  Serum levels of ionized calcium, phosphorus, PTH, 1,25D, and plasma C-terminal FGF23 levels were obtained at 0, 13, 30, 60, 90, and 120 minutes during the infusions.
  
  
  RESULTS
  During the calcium infusion, serum calcium concentrations increased from 1.33 ± 0.01 to 1.57 ± 0.04 mmol/L (P < .05 from baseline) and from 1.20 ± 0.05 to 1.50 ± 0.03 mmol/L (P < .05 from baseline) in healthy subjects and in dialysis patients, respectively, whereas serum calcium values decreased from 1.33 ± 0.01 to 1.03 ± 0.02 mmol/L (P < .05 from baseline) and from 1.26 ± 0.04 to 1.07 ± 0.03 mmol/L (P < .05 from baseline) in the two groups, respectively during the sodium citrate infusion. PTH levels decreased from 35 (29, 57) to 8 (2,10) pg/mL (healthy subjects) (P < .05 from baseline) and from 292 (109, 423) to 44 (28, 86) pg/mL (dialysis patients) (P < .05 from baseline) during the calcium infusion and rose from 31 (25, 56) to 122 (95, 157) pg/mL and from 281 (117, 607) to 468 (169, 928) pg/mL (P < .05 from baseline) during sodium citrate infusion. Serum 1,25D levels and plasma FGF23 values remained unchanged during both infusions in both groups.
  
  
  CONCLUSIONS
  Short-term changes in calcium and PTH levels do not affect FGF23 concentrations in either healthy volunteers or dialysis patients.
authors: Department of Pediatrics (K.W.-P., H.W., R.E., B.G., I.B.S.), David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, California 90095; and Endocrine Unit and Division of Pediatric Nephrology (H.J.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114.
authors: Katherine
authors: K
authors: Wesseling-Perry
authors: Hejing
authors: H
authors: Wang
authors: Robert
authors: R
authors: Elashoff
authors: Barbara
authors: B
authors: Gales
authors: Harald
authors: H
authors: Jüppner
authors: Isidro B
authors: IB
authors: Salusky
mesh_terms: D000293:Adolescent; D002118:Calcium / Q000008:administration & dosage / Q000097:blood*; D002951:Citrates / Q000008:administration & dosage; D025461:Feedback, Physiological / Q000187:drug effects / Q000502:physiology; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000378:metabolism* / Q000628:therapy; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood*; D010758:Phosphorus / Q000097:blood; D006435:Renal Dialysis; D000077559:Sodium Citrate; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D055815:Young Adult
chemical_list: D002951:Citrates; C000717427:FGF23 protein, human; D010281:Parathyroid Hormone; D014807:Vitamin D; D000077559:Sodium Citrate; D010758:Phosphorus; D005346:Fibroblast Growth Factors; C097949:1,25-dihydroxyvitamin D; D000089703:Fibroblast Growth Factor-23; D002118:Calcium