title: Limited utility of tartrate-resistant acid phosphatase isoform 5b in assessing response to therapy in osteoporosis.
abstract: BACKGROUND
  Tartrate-resistant acid phosphatase isoform 5b (TRACP5b) is a serum bone resorption marker. Our aim was to investigate its utility in monitoring metabolic bone disease.
  
  
  METHODS
  Serum TRACP5b, C-terminal cross-linking telopeptide of type I collagen, urine N-terminal cross-linking telopeptide of type I collagen and free deoxypyridinoline were measured pre- and post-treatment with a parathyroid hormone analogue [PTH (1-34)] (n = 14) or a bisphosphonate (N-BP) (n = 8). TRACP5b, bone alkaline phosphatase (bone ALP), 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) were measured in 100 osteoporosis patients on prolonged bisphosphonate therapy.
  
  
  RESULTS
  Changes in TRACP5b were smaller in magnitude but mimicked those of other bone resorption markers. Absolute changes in TRACP5b and the other resorption markers correlated significantly (p < 0.001). In patients on long-term bisphosphonates, TRACP5b and bone ALP levels were not suppressed. Vitamin D status was consistent with the level of supplementation.
  
  
  CONCLUSIONS
  TRACP5b has limited utility as a single marker of metabolic bone disease treatment.
authors.affiliation: Metabolism Laboratory, St. Vincent's University Hospital, Dublin, Ireland, jbrady@mater.ie.
authors.forename: J J
authors.initials: JJ
authors.lastname: Brady
authors.forename: R K
authors.initials: RK
authors.lastname: Crowley
authors.forename: B F
authors.initials: BF
authors.lastname: Murray
authors.forename: M T
authors.initials: MT
authors.lastname: Kilbane
authors.forename: M
authors.initials: M
authors.lastname: O'Keane
authors.forename: M J
authors.initials: MJ
authors.lastname: McKenna
mesh_terms: D000135:Acid Phosphatase / Q000097:blood*; D000368:Aged; D000369:Aged, 80 and over; D000469:Alkaline Phosphatase / Q000097:blood; D000596:Amino Acids / Q000097:blood; D015415:Biomarkers / Q000097:blood; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D001862:Bone Resorption / Q000097:blood / Q000188:drug therapy* / Q000201:enzymology; D024042:Collagen Type I / Q000097:blood; D004164:Diphosphonates / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000097:blood / Q000188:drug therapy* / Q000201:enzymology; D010281:Parathyroid Hormone / Q000097:blood; D010455:Peptides / Q000097:blood; D011237:Predictive Value of Tests; D000071681:Tartrate-Resistant Acid Phosphatase; D019379:Teriparatide / Q000031:analogs & derivatives / Q000627:therapeutic use*; D013997:Time Factors; D016896:Treatment Outcome; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
chemical_list: D000596:Amino Acids; D015415:Biomarkers; D050071:Bone Density Conservation Agents; D024042:Collagen Type I; D004164:Diphosphonates; D007527:Isoenzymes; C470125:PTH protein, human; D010281:Parathyroid Hormone; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D019379:Teriparatide; D014807:Vitamin D; C036020:deoxypyridinoline; C104450:25-hydroxyvitamin D; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase