title: Correlations and time course of FGF23 and markers of bone metabolism in maintenance hemodialysis patients.
abstract: OBJECTIVE
  Parathyroid hormone (iPTH) and fibroblast growth factor 23 (FGF23) are elevated in secondary hyperparathyroidism. In hemodialysis, higher dialysate calcium (1.5 mmol/L) induces intradialytic suppression of iPTH, whereas its impact on FGF23 and markers of bone metabolism is unknown. We assessed the time course of FGF23 and markers of bone metabolism in relationship to dialysate calcium.
  
  
  METHODS
  In this prospective cohort study of 19 patients on maintenance hemodialysis, we measured serum calcium (sCa), inorganic phosphate (iP), blood urea nitrogen (BUN), β2-microglobulin (ßMG), iPTH, FGF23, aminoterminal propeptide type 1 procollagen (P1NP), C-telopeptide of type I collagen for bone degradation (CTX-I), osteocalcin (OC), bone specific alkaline phosphatase (BALP), and tartrate-resistant acid phosphatase (TRAP5b) during a single hemodialysis session at baseline, 1, 2, and 3h of dialysis. The time course of measured parameters was compared according to groups of prescribed dialysate calcium of 1.25 mmol/L and 1.5 mmol/L.
  
  
  RESULTS
  iPTH declined in the 1.5 mmol/L dialysis group as serum calcium increased whereas it tended to increase in the 1.25 mmol/L group without significant changes in serum calcium. Patients on long-term dialysate calcium of 1.5 mmol/L had significantly lower CTX-I levels and tended to lower levels of iPTH, FGF23, OC, P1NP and TRAP5b at the start of dialysis compared to those on 1.25 mmol/L. CTX-I, FGF23 and OC but not BALP, P1NP and TRAP5b decreased during dialysis independent of dialysate calcium.
  
  
  CONCLUSIONS
  In spite of immediate effects on iPTH, dialysate calcium does not acutely affect other parameters of bone and mineral metabolism.
  
  
  OBJECTIVE
  Dialysate calcium concentration is known to have both immediate and longer-term impact on parathyroid hormone levels in hemodialysis patients. Little is known about the acute impact of dialysate calcium on bone metabolism. In this cross-sectional study of prevalent hemodialysis patients, we found no evidence of immediate short-term dialysate calcium-induced changes of fibroblast growth factor 23 or anabolic and catabolic markers of bone turnover during hemodialysis. However, differences in CTX-I and to a lesser extent other parameters between groups of higher and lower dialysate calcium suggest a longer-term effect that remains to be validated.
authors: Division of Nephrology and Dialysis, Department of Medicine III, Medical University of Vienna, Vienna, Austria. Electronic address: bernhard.bielesz@meduniwien.ac.at.
authors: Bernhard O
authors: BO
authors: Bielesz
authors: Division of Nephrology and Dialysis, Department of Medicine III, Medical University of Vienna, Vienna, Austria.
authors: Manfred
authors: M
authors: Hecking
authors: Division of Nephrology and Dialysis, Department of Medicine III, Medical University of Vienna, Vienna, Austria.
authors: Max
authors: M
authors: Plischke
authors: Division of Nephrology and Dialysis, Department of Medicine III, Medical University of Vienna, Vienna, Austria.
authors: Daniel
authors: D
authors: Cejka
authors: Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria.
authors: Heidi
authors: H
authors: Kieweg
authors: Division of Nephrology and Dialysis, Department of Medicine III, Medical University of Vienna, Vienna, Austria.
authors: Martin
authors: M
authors: Haas
authors: Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria.
authors: Rodrig
authors: R
authors: Marculescu
authors: Division of Nephrology and Dialysis, Department of Medicine III, Medical University of Vienna, Vienna, Austria.
authors: Walter H
authors: WH
authors: Hörl
authors: Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria.
authors: Christian
authors: C
authors: Bieglmayer
authors: Division of Nephrology and Dialysis, Department of Medicine III, Medical University of Vienna, Vienna, Austria.
authors: Gere
authors: G
authors: Sunder-Plassmann
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000469:Alkaline Phosphatase / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism*; D001806:Blood Urea Nitrogen; D001842:Bone and Bones / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D024042:Collagen Type I / Q000378:metabolism; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D015675:Osteocalcin / Q000378:metabolism; D010281:Parathyroid Hormone / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D011347:Procollagen / Q000378:metabolism; D011446:Prospective Studies; D006435:Renal Dialysis / Q000379:methods; D000071681:Tartrate-Resistant Acid Phosphatase
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; C000717427:FGF23 protein, human; D007527:Isoenzymes; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D010455:Peptides; D010710:Phosphates; D011347:Procollagen; C052929:collagen type I trimeric cross-linked peptide; C047202:procollagen Type I N-terminal peptide; D015675:Osteocalcin; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D002118:Calcium
keywords: C-telopeptide; Dialysis solutions; FGF23 protein, human; Hyperparathyroidism secondary; Inorganic phosphates; Osteocalcin; Parathyroid hormone; Renal dialysis; Renal insufficiency, chronic